Skocz do pozycji: 1.

Tytuł:

Validation of a flow channel to investigate velocity profiles of friction-reducing ship coatings

Autorzy:

Weisheit, J.
Schneider, V. E.
Serr, J. M.
Hagemeister, N.
Oeffner, J.

Powiązania:

https://bibliotekanauki.pl/articles/1841545.pdf

Data publikacji:

2021

Wydawca:

Uniwersytet Morski w Gdyni. Wydział Nawigacyjny

Tematy:

ship coatings
flow Channel
vessel velocity
laser Doppler velocimeter
computational fluid dynamics
AIRCOAT project
reynolds averaged navier stokes
measurement volume

Opis:

Reducing friction with specialised hull coatings or air lubrication technologies has a potential reducing energy consumption and emissions in shipping. The EU project AIRCOAT combines both by developing a passive air lubrication technology inspired by nature that is implemented on a self-adhesive foil system. Besides validating the friction reduction it is of high interest to understand the underlying mechanism that causes the reduction. Therefore, a flow channel was designed, that creates a stationary turbulent flow within a square duct allowing for non-invasive measurements by laser doppler velocimetry. The high spatial resolution of the laser device makes recording velocity profiles within the boundary layer down to the viscous sublayer possible. Determination of the wall shear stress τ enables direct comparison of different friction reduction experiments. In this paper we validate the methodology by determining the velocity profile of the flat channel wall (without coatings). We further use the results to validate a CFD model in created in OpenFOAM. We find that velocities along the longitudinal axis are generally in good agreement between numerical and experimental investigations.

Źródło:

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2021, 15, 1; 225-231
2083-6473
2083-6481

Pojawia się w:

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 2.

Tytuł:

Definition of dimensionless coefficient of resistance and coefficient of roughness in cross-section of stream with large roughness element

Autorzy:

Michalec, B.
Strutynski, M.

Powiązania:

https://bibliotekanauki.pl/articles/59718.pdf

Data publikacji:

2010

Wydawca:

Polska Akademia Nauk. Stowarzyszenie Infrastruktura i Ekologia Terenów Wiejskich PAN

Tematy:

Rudawa River
Bedkowka Stream
stream
large roughness grain
dimensionless coefficient
roughness coefficient
hydraulic condition
water flow
flow channel bottom
flow channel distribution

Opis:

The results of investigations carried out in the stream Będkówka – a left bank tributary of the Rudawa River are presented in this paper. A stream sector with large roughness element was chosen for investigations. The performed measurements included cross-section leveling and longitudinal leveling of the stream channel, bed load (sediment) sampling, and hydrometric measurements. Cross section leveling included five cross-sections in the 19-m long stream sector; these were located upstream and downstream the large roughness element and in its region. Differentiation of flow velocity in the region of large roughness element and its influence on differentiation of the load granulometric composition in the stream channel was shown. Immediately downstream the large roughness grain zone a fine grain sediment was frapped, its diameter d50 was seven to ten times smaller than that of the sediment in bed present in the stream channel. The dimensionless coefficient of resistance was calculated taking into account the equivalent bottom roughness determined in each of the examined sections by use of Gladki`s formulae. It was found that the large roughness element in the Będkówka stream caused a change of hydraulic conditions of water flow and, in consequence, the dimensionless coefficient of resistance in the grain section increased by about four times. The coefficient of channel roughness was also determined and it was shown that the coefficient of roughness in the section of large roughness element determined with consideration of the determined dimensionless coefficient of resistance increased on the average in the section of large roughness grain by over 34% in relation to the coefficient of channel roughness.

Źródło:

Infrastruktura i Ekologia Terenów Wiejskich; 2010, 11
1732-5587

Pojawia się w:

Infrastruktura i Ekologia Terenów Wiejskich

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 3.

Tytuł:

Preliminary calculations of flow in channel with triangular and rectangular obstacle

Autorzy:

Kmiotek, M.
Kucaba-Pietal, A.

Powiązania:

https://bibliotekanauki.pl/articles/1955312.pdf

Data publikacji:

2010

Wydawca:

Politechnika Gdańska

Tematy:

fluid flow
flow in a channel
CFD

Opis:

The paper presents the results of preliminary numerical calculations of a fluid flow in a channel with an obstacle. The flow problem was solved with an application of the finite elements method. Various geometries of obstacles were considered.

Źródło:

TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2010, 14, 4; 329-337
1428-6394

Pojawia się w:

TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 4.

Tytuł:

Organizacja badań diagnostycznych okrętowego tłokowego silnika spalinowego o ograniczonej podatności kontrolnej
Organization of diagnostic investigations of marine engine of limited monitoring susceptability

Autorzy:

Korczewski, Z.
Zacharewicz, M.

Powiązania:

https://bibliotekanauki.pl/articles/222576.pdf

Data publikacji:

2009

Wydawca:

Akademia Marynarki Wojennej. Wydział Dowodzenia i Operacji Morskich

Tematy:

diagnostyka
silniki okrętowe
doładowanie
kanały przepływowe
diagnostics
marine engines
supercharging
flow channel

Opis:

W artykule przedstawiono założenia wstępne opracowywanej w Akademii Marynarki Wojennej metody diagnozowania przestrzeni roboczych okrętowych tłokowych silników spalinowych o ograniczonej podatności kontrolnej niewyposażonych standardowo w zawory indykatorowe. Sformułowano problem badawczy oraz główne cele prowadzonych badań. Zdefiniowano pojęcie przestrzeni roboczych silnika oraz dokonano analizy czynników mających wpływ na degradację ich struktury konstrukcyjnej. Przeprowadzono dyskusję nad stosowanymi obecnie strategiami eksploatacji silników okrętowych, tzn. eksploatacją według resursu godzinowego, stanu technicznego oraz poziomu niezawodności. Scharakteryzowano zależności istniejące pomiędzy poszczególnymi stanami obiektu diagnozowania - przestrzeniami roboczymi silnika okrętowego. Prowadzone w artykule rozważania przedstawione zostały na tle osiągnięć zagranicznych i krajowych ośrodków naukowo-badawczych zajmujących się podejmowanym projektem badawczym. Pozwoliło to na doprecyzowanie schematu realizacji badań procesów gazodynamicznych dla celów diagnostyki okrętowego tłokowego silnika spalinowego.
The paper presents preliminary assumptions of the new diagnostic method concerning the marine diesel engine's workspace areas, which was developed at the Polish Naval Academy. It is expected that the method will be very useful to diagnose technical condition of marine diesel engines at limited monitoring susceptibility, i.e. the ones which are not equipped with indicator valves. It includes the research problem and main purposes of the research. The paper defines the notion of the workspace areas and does an analysis of factors that have the highest impact on destruction phenomenon. The paper also considers strategies used at present to run marine diesel engines: according to the engine installation life, according to the technical shape as well as according to the level of reliability. It characterises mutual interdependences between characteristic technical conditions of the research object (workspace areas). The research conducted is shown at the background of achievements of foreign and national scientific centres. This way the research diagram of gas-dynamical processes was made more precise for diagnostic purposes of marine diesel engines.

Źródło:

Zeszyty Naukowe Akademii Marynarki Wojennej; 2009, R. 50 nr 2 (177), 2 (177); 41-56
0860-889X

Pojawia się w:

Zeszyty Naukowe Akademii Marynarki Wojennej

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 5.

Tytuł:

LES of converging-diverging channel flow with separation

Autorzy:

Kuban, L.
Elsner, W.
Tyliszczak, A.

Powiązania:

https://bibliotekanauki.pl/articles/1943209.pdf

Data publikacji:

2010

Wydawca:

Politechnika Gdańska

Tematy:

LES
turbulent boundary layer
separation
channel flow
pressure gradient

Opis:

The paper presents the results of LES simulation of two different turbulent channels with inlet conditions corresponding to the Reynolds number Re =395. In both cases a varying pressure gradient was obtained by an adequate curvature of one of the walls. The first case is treated as a benchmark and is used to validate the numerical procedure. This case is characterized by the same cross-section area at the inlet and outlet and a bump of a smooth profile located on one of the walls designed to be identical to the one used in the experiment conducted at Laboratorie de Mecanique de Lille (LML) (Marquillie et al., 2008). The second case corresponds to the geometry which reproduces the real geometry of the turbomachinery test section of the Czestochowa University of Technology. The test section was created in such a way as to produce the pressure gradient which would correspond to the conditions present in the axial compressor blade channel. The shape of both channels produced initially favorable (FPG) and then adverse pressure gradients (APG), and in this way created conditions for boundary layer separation. Due to a reverse flow where the turbulence transport is dictated by the dynamics of the large-scale eddies such a case is well suited to demonstrate predictive features of the LES technique.

Źródło:

TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2010, 14, 3; 283-295
1428-6394

Pojawia się w:

TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 6.

Tytuł:

Shear Stress Statistics in a Compound Channel Flow

Autorzy:

Czernuszenko, W.
Rowiński, P. M.

Powiązania:

https://bibliotekanauki.pl/articles/241044.pdf

Data publikacji:

2008

Wydawca:

Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN

Tematy:

open channels
turbulence
measurements
Reynolds stresses
coherent structures

Opis:

The results of comprehensive measurements of three-dimensional turbulent velocities carried out in a laboratory compound channel are presented. Tests were performed in a two-stage channel with a smooth main channel bed consisting of concrete and rough floodplains and sloping banks. Instantaneous velocities were measured with the use of a three-component acoustic Doppler velocimeter. The main aim of the study is the recognition of structure of Reynolds stresses in turbulent open channel flows. Particular attention has been paid to bursting events such as ejections and sweeps. The bursting phenomenon occurs originally near the buffer layer and then shows a coherent or organized flow structure during its convection process. The probability density distributions of the turbulent velocities were measured at different distances from the bed in the main channel and also above the inclined walls. In the main channel, the lateral turbulent velocity is seen to follow the normal Gaussian distribution more closely than the remaining two components. Above the inclined walls, all distributions turned out to have greater skewness. The probability density distributions of correlations between velocity fluctuations were also calculated. These distributions have long tails and sharp peaks and fit the theoretical distributions very well. The structure of instantaneous Reynolds stresses was analyzed by a quadrant technique with an arbitrarily chosen threshold level. It has been shown that the largest contribution to turbulent stresses comes from the second quadrant (ejection) and the fourth quadrant (sweep). The basic temporal characteristics for quadrant events, like the average and maximum time for a zero hole size, have been determined in the study. Calculations of maximum duration times for all events reveal that times are greater for even quadrants than for odd quadrants.

Źródło:

Archives of Hydro-Engineering and Environmental Mechanics; 2008, 55, 1-2; 3-27
1231-3726

Pojawia się w:

Archives of Hydro-Engineering and Environmental Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 7.

Tytuł:

Numerical simulation of open channel flow between bridge piers

Autorzy:

Szydłowski, M.

Powiązania:

https://bibliotekanauki.pl/articles/1934025.pdf

Data publikacji:

2011

Wydawca:

Politechnika Gdańska

Tematy:

numerical simulation
open channel flow
mathematical modeling
bridge piers

Opis:

Free-surface flow in the vicinity of bridge piers on a fixed channel bed is a classical problem of open-channel hydraulics. This problem is usually analyzed using one-dimensional hydraulic models for steady-flow problems. The aim of this paper is to present a two-dimensional numerical simulation of water flow around obstacles, such as cylinders, which can act as a simplified model of real piers. The depth-averaged Navier-Stokes equations describing unsteady free-surface flow are solved using an explicit scheme of the finite-volume method. The numerical solution prepared for the simulations of unsteady free-surface flows was used here to analyze the case of steady flow. A numerical simulation of flow in the channel with the obstruction was performed for two different inflow discharges determining, respectively, the subcritical and supercritical flow in the cross-section of a channel constriction. In the second simulation, a hydraulic jump was observed downstream of the bridge section. The numerical results were compared with measurements. Water surface profiles were measured for both discharges in the hydraulic laboratory of the Faculty of Civil and Environmental Engineering at Gdansk University of Technology (GUT). Comparisons with laboratory data showed that the proposed approach constitutes a sufficiently accurate and reliable technique for predicting basic flow parameters. The method of two-dimensional modeling of flow in a river channel between bridge piers can be also integrated with the simulation of unsteady flood wave propagation, ensuring a uniform approach to the problem of flood modeling in river valleys. Moreover, a two-dimensional simulation yields detailed information about flow structure near the obstruction, which can be used to better elucidate debris transport and river bed deformation processes.

Źródło:

TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2011, 15, 3-4; 271-282
1428-6394

Pojawia się w:

TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 8.

Tytuł:

Numerical simulation of channel flow over a skewed equilateral cavity

Autorzy:

Kamel, Abanoub G.
Haraz, Eman H.
Hanna, Sarwat N.

Powiązania:

https://bibliotekanauki.pl/articles/1839759.pdf

Data publikacji:

2020

Wydawca:

Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej

Tematy:

finite difference method
incompressible flow
channel flow
lid-driven
shear-driven
skewed cavity
Navier-Stokes equations
równanie Naviera-Stokesa
przepływ nieściśliwy
metoda różnic skończonych
przepływ kanałowy

Opis:

In this paper, an incompressible, two-dimensional (2D), time-dependent, Newtonian, laminar, and internal channel fluid flow over a skewed equilateral cavity is simulated using the finite difference method (FDM) and alternating direction implicit (ADI) technique. Navier-Stokes equations are solved numerically in stream function-vorticity formulation. The goal of tackling this problem depends on its academic significance by studying the difference between lid-driven and shear-driven cavity flows in terms of the formation of Moffatt eddies at the sharp corner, also to obtain the length and intensity ratios of these counter-rotating vortices. The value of velocity components along the centerlines of the skewed cavity was revealed at low and intermediate Reynolds numbers (Re), typically (Re = 200 and 2000) at two different skew angles of mainly 30° and 45°. Likewise, the blocked-off regions’ method is used to deal with the geometry of the skewed cavity especially the sharp corners. Furthermore, as Re increases, the main vortex approaches the skewed cavity center and the counter-rotating vortices get bigger in size and intensity, and their number increases.

Źródło:

Journal of Applied Mathematics and Computational Mechanics; 2020, 19, 3; 29-43
2299-9965

Pojawia się w:

Journal of Applied Mathematics and Computational Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 9.

Tytuł:

Radiation effect on three dimensional vertical channel flow through porous medium

Autorzy:

Guria, M.

Powiązania:

https://bibliotekanauki.pl/articles/265265.pdf

Data publikacji:

2015

Wydawca:

Uniwersytet Zielonogórski. Oficyna Wydawnicza

Tematy:

three-dimensional
injection
periodic suction
permeability
porous medium
porowatość
promieniowanie
chłodzenie

Opis:

The flow of a viscous incompressible fluid through a vertical channel in the presence of radiation immersed in a porous medium has been studied. Approximate solutions have been obtained for the velocity and temperature fields, shear stresses and rate of heat transfer using the perturbation technique. It is found that the primary velocity decreases with an increase in the radiation parameter as well as the Prandtl number for cooling of the plate. It is also found that with an increase in the permeability parameter, the primary velocity increases for cooling of the plate. The magnitude of the secondary velocity decreases near the plate y = 0 and increases near the plate y = d with an increase in the permeability parameter. The temperature distribution decreases with an increase of the radiation parameter as wall as the Prandtl number for cooling of the plate. The shear stresses and the rate of heat transfer, which are of physical interest, are presented in the form of tables.

Źródło:

International Journal of Applied Mechanics and Engineering; 2015, 20, 4; 817-833
1734-4492
2353-9003

Pojawia się w:

International Journal of Applied Mechanics and Engineering

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 10.

Tytuł:

Efficient implementation of a compact-pseudospectral method for turbulence modeling

Autorzy:

Tyliszczak, A.

Powiązania:

https://bibliotekanauki.pl/articles/1955215.pdf

Data publikacji:

2006

Wydawca:

Politechnika Gdańska

Tematy:

large eddy simulation
compact scheme
channel flow

Opis:

The paper is devoted to parallel implementation of a compact discretization scheme com-bined with the Fourier pseudospectral method. The idle time of processors resulting from the method of computating derivatives using compact schemes is eliminated by proper ordering of subtasks and by performing useful computations when processors are waiting for data from their neighbors. The correctnes of the algorithm is confirmed by comparison of results of LES simulations with DNS data for flow in a 3D channel with periodic non-slip wall boundary conditions.

Źródło:

TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2006, 10, 2; 125-138
1428-6394

Pojawia się w:

TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 11.

Tytuł:

Modelling the gas flow in permeate channel in membrane gas separation process

Autorzy:

Szwast, M.

Powiązania:

https://bibliotekanauki.pl/articles/185832.pdf

Data publikacji:

2018

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

gas separation
perfect mixing
Peclet number
CFD
separacja gazów
mieszanie

Opis:

This paper analyses the real behaviour of the fluid in the channels of a three-end membrane module. The commonly accepted mathematical model of membrane separation of gas mixtures in such modules assumes a plug flow of fluid through the feed channel and perfect mixing in the permeate channel. This article discusses the admissibility of accepting such an assumption regarding the fluid behaviour in the permeate channel. Throughout analysis of the values of the Péclet number criterion, it has been demonstrated that in the industrial processes of membrane gas separation, the necessary conditions for the perfect mixing in the permeate channel are not met. Then, CFD simulations were performed in order to establish the real fluid behaviour in this channel. It was proved that in the permeate channel the fluid movement corresponds to the plug flow, with the concentration differences at both ends of the module being insignificant. In view of the observations made, the admissibility of concentration stability assumptions in the mathematical models for the permeate channel was discussed.

Źródło:

Chemical and Process Engineering; 2018, 39, 3; 271--280
0208-6425
2300-1925

Pojawia się w:

Chemical and Process Engineering

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 12.

Tytuł:

Determination of selected parameters in a 1D open channel flow model

Autorzy:

Weinerowska-Bords, K.

Powiązania:

https://bibliotekanauki.pl/articles/1933161.pdf

Data publikacji:

2007

Wydawca:

Politechnika Gdańska

Tematy:

determination of parameters
optimization procedures
well-posed and ill-posed problems
numerical methods

Opis:

Determination of the model's parameters is an important stage of mathematical models' application. In the case of a free-surface ID unsteady flow model defined by the de Saint- Venant equations, one of the groups of parameters to be estimated is the set of parameters describing energy losses due to friction. The parameters can be estimated in different ways, but in most cases the task of their determination is an ill-posed problem. In such cases, optimi-zation methods are the most common approach. In spite of numerous examples of such applications, these techniques are still not fully recognized, as there are several problems of different nature that require thorough analysis. Automatic optimization methods are discussed in the paper. The most important questions of choosing the objective function and the optimization algorithm are considered. Problems connected with data reliability and accessibility and their influence on the solution are discussed. The most common pitfalls of optimization applications are discussed. The analysis is supported with numerical examples.

Źródło:

TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2007, 11, 4; 341-364
1428-6394

Pojawia się w:

TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 13.

Tytuł:

Lagrangian Model for a Single Saltating Grain in the Near-Wall Region of an Open-Channel Flow

Autorzy:

Czernuszenko, W.

Powiązania:

https://bibliotekanauki.pl/articles/241181.pdf

Data publikacji:

2013

Wydawca:

Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN

Tematy:

Lagrangian model
open-channel flow
particle-particle interaction

Opis:

A mathematical model for the continuous saltation of a particle near the granular bed in an open-channel flow is developed in detail. The model is based on the Lagrangian equations governing particle motion, and it takes into account the following forces: drag, lift, gravitation, virtual mass and the force responsible for particle-particle interactions. A model of particle-particle collisions is developed and used to determine the mean impulsive force acting upon a particle flowing and rebounding from the channel bed. The model can simulate the continuous saltation trajectories of a single particle in the near-bed region of turbulent flows, in which particle motion is controlled by collisions. The model has been calibrated and verified with available published data in a rather wide range of grain sizes from 0.53 mm to 15 mm. All parameters, such as lift, drag, restitution, friction coefficients and roughness height, have been set on the basis of a reanalysis of these published data.

Źródło:

Archives of Hydro-Engineering and Environmental Mechanics; 2013, 60, 1-4; 31-50
1231-3726

Pojawia się w:

Archives of Hydro-Engineering and Environmental Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 14.

Tytuł:

Effect of slip condition on vertical channel flow in the presence of radiation

Autorzy:

Guria, M.

Powiązania:

https://bibliotekanauki.pl/articles/265192.pdf

Data publikacji:

2016

Wydawca:

Uniwersytet Zielonogórski. Oficyna Wydawnicza

Tematy:

wtrysk
odsysanie pływalności
płyn nienewtonowski
three-dimensional
injection
suction
buoyancy
transpiration cooling
free convection

Opis:

An analysis is made on the three dimensional flow of a viscous incompressible fluid through a vertical channel in the presence of radiation in slip flow regime. The right plate is subjected to an uniform injection and the left plate to a periodic suction velocity distribution. The velocity and temperature fields have been derived using the perturbation technique. It is found that the velocity decreases with the increase of the slip parameter. It is also found that the velocity decreases with the increase of the radiation parameter but near the right plate it increases. For cooling of the plate, the velocity increases with the increase of the Grashoff number and decreases near the right plate but the reverse effect is observed for heating the plate.

Źródło:

International Journal of Applied Mechanics and Engineering; 2016, 21, 2; 341-358
1734-4492
2353-9003

Pojawia się w:

International Journal of Applied Mechanics and Engineering

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 15.

Tytuł:

Modelling of near-wall turbulence with large-eddy velocity modes
Modelowanie turbulencji za pomocą wielkoskalowych modów prędkości

Autorzy:

Wacławczyk, M.
Pozorski, J.

Powiązania:

https://bibliotekanauki.pl/articles/279207.pdf

Data publikacji:

2007

Wydawca:

Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej

Tematy:

proper orthogonal decomposition
coherent structures
turbulent channel flow

Opis:

In the paper, low-order modelling of the turbulent velocity field in the near-wall region is performed using the Proper Orthogonal Decomposition (POD) approach. First, an empirical eigenfunction basis is computed, basing on two-point velocity correlations. Next, the Galerkin projection of the Navier-Stokes equations on the truncated basis is performed. This results in a system of Ordinary Differential Equations (ODEs) for time-dependent coefficients. Evolution of the largest vortical structures in the near-wall zone is then obtained from the time dependent coefficients and eigenfunctions. The system applied in the present work consists of 20 ODEs, the reconstructed velocity field is two-dimensional in the pIane perpendicular to the main flow direction. Moreover, the filtering procedure associated with the POD method is discussed, the POD filter is derived and compared with LES filters.
Przedmiotem pracy jest modelowanie turbulentnego pola prędkości w obszarze przyściennym za pomocą niskowymiarowego systemu dynamicznego, opartego o dekompozycję w bazie funkcji własnych POD (ang. Proper Orthogonal Decomposition). Empiryczna baza funkcyjna POD została wyznaczona z rozwiązania zagadnienia własnego, w którym obecne są dwupunktowe korelacje prędkości. Następnie, w wyniku projekcji Galerkina równań pędu na podprzestrzeń rozpiętą na tej bazie funkcyjnej, otrzymano układ równań różniczkowych zwyczajnych na zależne od czasu wspołczynniki. Na podstawie funkcji własnych oraz z wyznaczonych współczynników rozkładu uzyskano ewolucję w czasie charakterystycznych struktur wirowych w obszarze przyściennym. System dynamiczny rozpatrywany w pracy składa się z 20 równań różniczkowych zwyczajnych. Zrekonstruowane pole prędkości jest dwuwymiarowe (w płaszczyźnie prostopadłej do głównego kierunku przepływu). Ponadto w pracy dyskutowana jest procedura filtrowania związana z metodą POD. Wyprowadzony filtr POD porównano z formułą używaną w metodzie symulacji dużych wirów.

Źródło:

Journal of Theoretical and Applied Mechanics; 2007, 45, 3; 705-724
1429-2955

Pojawia się w:

Journal of Theoretical and Applied Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 16.

Tytuł:

Experimental and numerical analysis of the air flow in T-shape channel flow
Eksperymentalna i numeryczna analiza przepływu powietrza przez skrzyżowanie kanałów w kształcie litery T

Autorzy:

Szmyd, J.
Branny, M.
Karch, M.
Wodziak, W.
Jaszczur, M.
Nowak, R.

Powiązania:

https://bibliotekanauki.pl/articles/219603.pdf

Data publikacji:

2013

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

przepływ przez skrzyżowanie kanałów o kształcie T
PIV
walidacja kodów CFD
wentylacja kopalń
T-shape channel flow
validation of CFD codes
mining ventilation

Opis:

This paper presents the results of experimental and numerical investigations of air flow through the crossing of a mining longwall and ventilation gallery. The object investigated consists of airways (headings) arranged in a T-shape. Maintained for technological purposes, the cave is exposed particularly to dangerous accumulations of methane. The laboratory model is a certain simplification of a real longwall and ventilation gallery crossing. Simplifications refer to both the object’s geometry and the air flow conditions. The aim of the research is to evaluate the accuracy with which numerical simulations model the real flow. Stereo Particle Image Velocimetry (SPIV) was used to measure all velocity vector components. Three turbulence models were tested: standard k-ε, k-ε realizable and the Reynolds Stress Model (RSM). The experimental results have been compared against the results of numerical simulations. Good agreement is achieved between all three turbulence model predictions and measurements in the inflow and outflow of the channel. Large differences between the measured and calculated velocity field occur in the cavity zone. Two models, the standard k-ε and k-ε realizable over-predict the measure value of the streamwise components of velocity. This causes the ventilation intensity to be overestimated in this domain. The RSM model underestimates the measure value of streamwise components of velocity and therefore artificially decreases the intensity of ventilation in this zone. The RSM model provides better predictions than the standard k-ε and k-ε realizable in the cavity zone.
Przedmiotem badań jest walidacja wybranych modeli CFD (Computational Fluid Dynamics) przy przepływie powietrza przez laboratoryjny model skrzyżowania kanałów w kształcie litery T. Stanowisko laboratoryjne przedstawia uproszczony model skrzyżowania ściany z chodnikiem wentylacyjnym. Przyjęto, że przepływ powietrza jest ustalony i izotermiczny. Dla tych warunków z równości liczb Reynoldsa w modelu i obiekcie rzeczywistym wynika warunek podobieństwa uśrednionych pól prędkości (przy załozeniu nieściśliwości powietrza). Pomiar składowych wektora prędkości wykonano metodą SPIV (Stereo Particle Image Velocimetry). W pracy testowano trzy modele turbulencji: standardowy model k-ε, jego modyfikację k-ε „realizable” oraz model naprężeń Reynoldsa (Reynolds Stress Model). Obliczenia numeryczne dla warunków identycznych jak w eksperymencie wykonano przy zastosowaniu programu FLUENT. Zadawalającą zgodność pomiędzy pomiarami i obliczeniami wszystkimi trzema modelami turbulencji uzyskano w kanałach zarówno po stronie dopływu jak i wypływu strumieniem powietrza ze skrzyżowania. Natomiast w strefie wnęki żaden z testowanych modeli nie wykazał pełnej zgodności z wynikami eksperymentalnymi. Do oszacowania dokładności z jaką symulacje numeryczne odwzorowują przepływ rzeczywisty w strefie wnęki wykorzystano wskaźnik charakteryzujący czas zaniku cząstek znacznikowych wprowadzonych do przepływu. Obliczenia wykonano dla dwóch modeli turbulencji: standardowego k-ε oraz modelu RSM. Czas potrzebny do rozrzedzenia początkowej koncentracji gazu znacznikowego do określonego poziomu - w przedziale koncentracji względnej od 0,3 do 0,1 - uzyskany z obliczeń standardowym modelem k-ε jest krótszy o 32%-27% od czasu wynikającego z pomiarów podczas gdy model RSM przeszacowuje wartości mierzone wartości koncentracji gazu o 18%-27%. Dwa z testowanych modeli, mianowicie standardowy k-ε i k-ε „realizable” przeszacowują mierzone wartości składowych wzdłużnych wektora prędkości. Konsekwencją tego jest sztuczne zawyżenie intensywności wentylacji we wnęce. Z kolei model RSM niedoszacowuje mierzone wartości składowych wzdłużnych wektora prędkości co powoduje zaniżenie rzeczywistej intensywności wentylacji tej strefy. Z przeprowadzonych badań wynika, że w obszarze wnęki rezultaty uzyskane modelem RSM są bliższe do wartości mierzonych niż prognozowane standardowym modelem k-ε i modelem k-ε „realizable”.

Źródło:

Archives of Mining Sciences; 2013, 58, 2; 333-348
0860-7001

Pojawia się w:

Archives of Mining Sciences

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 17.

Tytuł:

Lax-Wendroff and McCormack Schemes for Numerical Simulation of Unsteady Gradually and Rapidly Varied Open Channel Flow

Autorzy:

Machalińska-Murawska, J.
Szydłowski, M.

Powiązania:

https://bibliotekanauki.pl/articles/973864.pdf

Data publikacji:

2013

Wydawca:

Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN

Tematy:

open channel flow
mathematical modeling
numerical simulation
FDM schemes

Opis:

Two explicit schemes of the finite difference method are presented and analyzed in the paper. The applicability of the Lax-Wendroff and McCormack schemes for modeling unsteady rapidly and gradually varied open channel flow is investigated. For simulation of the transcritical flow the original and improved McCormack scheme is used. The schemes are used for numerical solution of one dimensional Saint-Venant equations describing free surface water flow. Two numerical simulations of flow with different hydraulic characteristics were performed – the first one for the extreme flow of the dam-break type and the second one for the simplified flood wave propagation problem. The computational results are compared to each other and to arbitrary solutions.

Źródło:

Archives of Hydro-Engineering and Environmental Mechanics; 2013, 60, 1-4; 51-62
1231-3726

Pojawia się w:

Archives of Hydro-Engineering and Environmental Mechanics

Dostawca treści:

Biblioteka Nauki

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Skocz do pozycji: 18.

Tytuł:

Second law analysis of mhd forced convective nanoliquid flow through a two-dimensional channel

Autorzy:

Miri, Rached
Abbassi, Mohamed A.
Ferhi, Mokhtar
Djebali, Ridha

Powiązania:

https://bibliotekanauki.pl/articles/2204682.pdf

Data publikacji:

2022

Wydawca:

Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej

Tematy:

MHD
LBM
channel flow
nanoliquids
entropy generation
Brownian motion

Opis:

The present study deals with fluid flow, heat transfer and entropy generation in a two-dimensional channel filled with Cu–water nanoliquid and containing a hot block. The nanoliquid flow is driven along the channel by a constant velocity and a cold temperature at the inlet, and the partially heated horizontal walls. The aim of this work is to study the influence of the most important parameters such as nanoparticle volume fraction (0%≤ϕ≤4%), nanoparticle diameter (5 nm≤dp≤55 nm), Reynolds number (50≤Re≤200), Hartmann number (0≤Ha≤90), magnetic field inclination angle (0≤γ≤π) and Brownian motion on the hydrodynamic and thermal characteristics and entropy generation. We used the lattice Boltzmann method (LBM: SRT-BGK model) to solve the continuity, momentum and energy equations. The obtained results show that the maximum value of the average Nusselt number is found for case (3) when the hot block is placed between the two hot walls. The minimum value is calculated for case (2) when the hot block is placed between the two insulated walls. The increase in Reynolds and Hartmann numbers enhances the heat transfer and the total entropy generation. In addition, the nanoparticle diameter increase reduces the heat transfer and the irreversibility, the impact of the magnetic field inclination angle on the heat transfer and the total entropy generation is investigated, and the Brownian motion enhances the heat transfer and the total entropy generation.

Źródło:

Acta Mechanica et Automatica; 2022, 16, 4; 417--431
1898-4088
2300-5319

Pojawia się w:

Acta Mechanica et Automatica

Dostawca treści:

Biblioteka Nauki

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Skocz do pozycji: 19.

Tytuł:

On origin of unstable modes in viscous channel flow subject to periodically distributed surface suction
O pochodzeniu niestatecznych form zaburzeń w przepływie cieczy lepkiej w kanale z przestrzennie okresowym odsysaniem/wypływem

Autorzy:

Szumbarski, J.

Powiązania:

https://bibliotekanauki.pl/articles/281294.pdf

Data publikacji:

2002

Wydawca:

Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej

Tematy:

periodic channel flow
linear stability
Floquet theory
surface suction

Opis:

The linear stability of a flow in a channel subject to periodically distributed suction applied at the wallsis investigated. The focus is on the relation between unstable modes observed in such a flow and the stability properties of the flow without suction (the Poiseuille flow). It is demonstrated that linearly unstable modes appearing in the presence of suction can be interpreted as modified Orr-Sommerfeld's or Squire's eigenmodes of the Poiseuille flow. Originally, these modes have the streamwise wave number equal to zero, i.e. they are invariant in the streamwise direction. When the surface suction is applied, the modes are additionally modulated along the channel and they become dependent on the streamwise variable. In the range of the parameters studied, a pair of such modes, one Orr-Sommerfeld's and one Squire's, can be simultaneously unstable. Certain properties of these modes are discussed in some details. Specifically, the influence of non-symmetric suction on stability characteristics is analysed.
W pracy rozważa się zagadnienie liniowej stateczności przepływu cieczy w płaskim kanale, w obecności periodycznie rozłożonego odsysania/wypływu przez ściany. Celem analizy jest identyfikacja zaburzeń krytycznych i objaśnienia ich związku z rozwiązaniami własnymi zagadnienia stateczności dla przepływu Poiseuille'a. Stosując metodę kontynuacji wartości i rozwiązań własnych po parametrze wykazano, że obserwowane formy niestabilności to zmodyfikowane okresowo w kierunku przepływu poprzeczne, symatryczne mody Squire'a i Orra-Sommerfelda, którym odpowiadają czysto urojone wartości własne. Zbadano numerycznie wpływ parametrów odsysania/wypływu na własności tych modów.

Źródło:

Journal of Theoretical and Applied Mechanics; 2002, 40, 4; 847-871
1429-2955

Pojawia się w:

Journal of Theoretical and Applied Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 20.

Tytuł:

Numerical Modelling of Fish Passage with Turning Pools

Autorzy:

Maniecki, Ł.

Powiązania:

https://bibliotekanauki.pl/articles/241474.pdf

Data publikacji:

2018

Wydawca:

Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN

Tematy:

open channel flow
fishway
turbulence
numerical model
turning pool

Opis:

An assessment of operating conditions in a baffled fish passage with pool dimensions of 2:2 3:0 m, and 180 horizontally turning pools, was carried out using numerical computations and a site survey of water flow velocity distribution. Velocity was measured with a PMS electromagnetic flowmeter and a hydrometric current meter in representative cross-sections of the fish passage in the pool centres and in the baffle barrier cross-section area. Numerical computations were also performed for two alternative baffle locations in the fishway. One reflected the actual conditions, and the other was an alternative arrangement designed to improve hydraulic conditions for fish migration. The numerical model used the Large Eddy Simulation (LES) method, which makes it possible to detect large vortexes. The study pays close attention to the velocity field analysis as well as the distribution and sizes of vortexes in the turning pool of the culvert. The results of numerical computations and the site survey show high consistency, and the proposed baffle placement modification significantly improves flow conditions, especially in the entry section of the passage.

Źródło:

Archives of Hydro-Engineering and Environmental Mechanics; 2018, 65, 1; 41-66
1231-3726

Pojawia się w:

Archives of Hydro-Engineering and Environmental Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 21.

Tytuł:

Numerical analysis of open channel steady gradually varied flow using the simplified Saint-Venant equations

Autorzy:

Artichowicz, W.

Powiązania:

https://bibliotekanauki.pl/articles/1934022.pdf

Data publikacji:

2011

Wydawca:

Politechnika Gdańska

Tematy:

dynamic equation
open-channel flow
open-channel networks
steady flow

Opis:

For one-dimensional open-channel flow modeling, the energy equation is usually used. There exist numerous approaches using the energy equation for open-channel flow computations, which resulted in the development of several very efficient methods for solving this problem applied to channel networks. However, the dynamic equation can be used for this purpose as well. This paper introduces a method for solving a system of non-linear equations by the discretization of the one-dimensional dynamic equation for open-channel networks. The results of the computations using the dynamic and energy equations were compared for an arbitrarily chosen problem. Also, the reasons for the differences between the solution of the dynamic and energy equation were investigated.

Źródło:

TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2011, 15, 3-4; 317-328
1428-6394

Pojawia się w:

TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 22.

Tytuł:

Experimental Analysis of Relations Between Coherent Turbulent Structures and Formation of Bedforms

Autorzy:

Termini, D.
Sammartano, V.

Powiązania:

https://bibliotekanauki.pl/articles/241077.pdf

Data publikacji:

2008

Wydawca:

Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN

Tematy:

open channel flow
sediment transport
bed forms
flow turbulence structure

Opis:

The present paper describes an experimental investigation on the interactions between flow turbulence and sediment motion. During the experiments, detailed measurements of flow velocity components were carried out using an Acoustic Doppler Velocimeter (ADV). The occurrence of turbulent events (inward interaction, ejection, sweep and burst) was verified through conditioned quadrant analysis. The quantitative information on the spatial and temporal evolution of turbulent events was obtained through space-time correlations of the conditioned data. As the primary objective was to analyse how turbulent structures influence formation of bedforms, the spatial scale of turbulent event evolution has been compared with the wavelength of bed-forms (alternate bars) observed on the bed. The analysis has essentially highlighted that such spatial scale compares well with the wavelength of the bars.

Źródło:

Archives of Hydro-Engineering and Environmental Mechanics; 2008, 55, 3-4; 125-143
1231-3726

Pojawia się w:

Archives of Hydro-Engineering and Environmental Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 23.

Tytuł:

A Mathematical Model of Membrane Gas Separation with Energy Transfer by Molecules of Gas Flowing in a Channel to Molecules Penetrating this Channel from the Adjacent Channel

Autorzy:

Szwast, M.
Szwast, Z.

Powiązania:

https://bibliotekanauki.pl/articles/185043.pdf

Data publikacji:

2015

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

membrane
membrane module
reciprocal transfer of energy between gas molecules
changes of the pressure of gas along the length of flow channel
membrana
wzajemne przekazywanie energii między cząsteczkami gazu
zmiany ciśnienia gazu na długości kanału przepływowego

Opis:

The paper presents the mathematical modelling of selected isothermal separation processes of gaseous mixtures, taking place in plants using membranes, in particular nonporous polymer membranes. The modelling concerns membrane modules consisting of two channels – the feeding and the permeate channels. Different shapes of the channels cross-section were taken into account. Consideration was given to co-current and counter-current flows, for feeding and permeate streams, respectively, flowing together with the inert gas receiving permeate. In the proposed mathematical model it was considered that pressure of gas changes along the length of flow channels was the result of both – the drop of pressure connected with flow resistance, and energy transfer by molecules of gas flowing in a given channel to molecules which penetrate this channel from the adjacent channel. The literature on membrane technology takes into account only the drop of pressure connected with flow resistance. Consideration given to energy transfer by molecules of gas flowing in a given channel to molecules which penetrate this channel from the adjacent channel constitute the essential novelty in the current study. The paper also presents results of calculationsobtained by means of a computer program which used equations of the derived model. Physicochemical data concerning separation of the CO2/CH4 mixture with He as the sweep gas and data concerning properties of the membrane made of PDMS were assumed for calculations.

Źródło:

Chemical and Process Engineering; 2015, 36, 2; 151-169
0208-6425
2300-1925

Pojawia się w:

Chemical and Process Engineering

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 24.

Tytuł:

Hydraulic Loss Coefficients in 1D Flows

Autorzy:

Sawicki, J. M.

Powiązania:

https://bibliotekanauki.pl/articles/241418.pdf

Data publikacji:

2007

Wydawca:

Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN

Tematy:

hydraulic loss
closed-conduits flows
water hammer
open channel flow

Opis:

Determination of hydraulic losses is a very important problem, both from the cognitive and practical points of view. For the uniform and steady fluid streams these losses are described by the well known algebraic expressions, containing some experimental coefficients. In technical practice it is commonly assumed, that these coefficients can be applied also for more complex kinds of flow (non-uniform and even unsteady). However, the problem analysis shows that the proper level of conformity between the results of calculations and measurements can be obtained only after a considerable enlargement of the loss coefficient. Investigation of available characteristics of non-uniform and unsteady 1D velocity fields, presented in this article, leads to the conclusion that this enlargement is physically justified and in some cases it is possible to determine correction factors, which enable recalculation of "basic" coefficients into their new values, suitable for more complex models of 1D flows.

Źródło:

Archives of Hydro-Engineering and Environmental Mechanics; 2007, 54, 2; 95-116
1231-3726

Pojawia się w:

Archives of Hydro-Engineering and Environmental Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 25.

Tytuł:

Static instability of an inverted plate in channel flow: state-space representation and solution approximation

Autorzy:

Li, P.
Zhang, D.
Cui, J.
Yin, H.
Yang, Y.

Powiązania:

https://bibliotekanauki.pl/articles/38697113.pdf

Data publikacji:

2023

Wydawca:

Instytut Podstawowych Problemów Techniki PAN

Tematy:

inverted cantilevered plate
static aeroelastic instability
channel flow
state-space representation
Glauert’s series
the least squares method

Opis:

Plate-like structures in channel flow are commonly found in engineering. This paper reports a theoretical study on the static aeroelastic instability of an inverted cantilevered plate in an inviscid channel flow through the state space. This study begins with the kernel function of the flow potential determined in the Fourier domain with the help of the mirror image method. Then, the instability equation is derived from the operator theory and transformed in the state space. Finally, with Glauert’s expansion, model functions, and error functions, the instability problem of such a plate has been modeled as a mathematical function approximation problem and solved by the least squares method. The derived instability equation is considered at the continuum level of description, and no approximation appears at the first equation level. The convergence and reliability of the proposed modeling and its solutions approximation are entirely tested, and it can successfully predict the instability boundary, behavior, and the channel effect. Numerical results show that the decreased channel height and asymmetric plate placement in the channel significantly decrease the critical flow velocity. The plate instability modes are close to the plate’s first natural ones and not sensitive to the channel parameters. This conclusion allows further theoretical exploration of a semi-analytical approximation of the instability boundary from the obtained instability equation. The current modeling strategy in a continuum sense may provide a new idea and essential reference for other instability problems.

Źródło:

Archives of Mechanics; 2023, 75, 6; 695-727
0373-2029

Pojawia się w:

Archives of Mechanics

Dostawca treści:

Biblioteka Nauki

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Skocz do pozycji: 26.

Tytuł:

Pulsatile Powell-Eyring nanofluid flow in a channel with inclined magnetic field and chemical reaction

Autorzy:

Srinivas, Suripeddi
Challa, Kalyan Kumar
Badeti, Satyanarayana
Kumar, P. Bharath

Powiązania:

https://bibliotekanauki.pl/articles/38912302.pdf

Data publikacji:

2023

Wydawca:

Instytut Podstawowych Problemów Techniki PAN

Tematy:

Powell-Eyring nanofluid
inclined magnetic field
chemical reaction
pulsatile flow
mass flux

Opis:

The current article addresses the impacts of the pulsatile flow of Powell-Eyring nanofluid using Buongiorno’s model in a horizontal channel. It also describes the combined impacts of thermophoresis and Brownian motion. Blood is an example of a Powell-Eyring fluid. The Runge-Kutta (R-K) 4th-order method, along with the shooting technique, is used to determine solutions for velocity, temperature, and concentration. The impacts of different parameters, including an inclined magnetic field, chemical reaction, Lewis number, and heat source or sink parameter, are illustrated graphically. The mass flux distribution decreases due to an increase in the values of the Powell-Eyring fluid parameter.

Źródło:

Engineering Transactions; 2023, 71, 4; 519-535
0867-888X

Pojawia się w:

Engineering Transactions

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 27.

Tytuł:

The application of cumulants to flow routing

Autorzy:

Romanowicz, Renata J.
Doroszkiewicz, Joanna

Powiązania:

https://bibliotekanauki.pl/articles/108562.pdf

Data publikacji:

2019

Wydawca:

Instytut Meteorologii i Gospodarki Wodnej - Państwowy Instytut Badawczy

Tematy:

open channel flow
linearized St. Venant equation
analytical solutions
moments
cumulants

Opis:

This paper aims to fill a gap between present and past research approaches to modelling flow in open channels. In particular, a history of the analytical solutions of a linearized St. Venant equation is presented. A solution of the linearized St. Venant equation, describing the response of a river channel to a single impulse forcing, the so called Instantaneous Unit Hydrograph (IUH), can be described using cumulants, defined as the moments of a logarithm of a variable. A comparison of analytical and numerical solutions of flood wave propagation under various flow conditions is given. The river reach of Biała Tarnowska is used as an illustration of both approaches. A practical application of simplified solutions to the emulator of a flood wave propagation is suggested showing a link between theory and practice.

Źródło:

Meteorology Hydrology and Water Management. Research and Operational Applications; 2019, 7, 1; 15-21
2299-3835
2353-5652

Pojawia się w:

Meteorology Hydrology and Water Management. Research and Operational Applications

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 28.

Tytuł:

Alluvial bottom geology inferred as a factor controlling channel flow along the Middle Vistula River, Poland

Autorzy:

Falkowski, T.

Powiązania:

https://bibliotekanauki.pl/articles/2059483.pdf

Data publikacji:

2007

Wydawca:

Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy

Tematy:

alluvial basement
erosion resistant deposits
Middle Vistula River Valley
channel zone
stream zone

Opis:

Within the channel zone of the Middle Vistula River, elevations of the Holocene alluvial basement occur, composed of deposits resistant to erosion. In this paper two kinds of such forms are discussed. Within the Małopolska gorge (an upstream part of the Middle Vistula, near Kępa Gostecka and Zakrzów), the elevations are composed mainly of Upper Cretaceous and Paleogene rocks covered with clayey debris and residual lags. Below this, the elevations are built of Paleogene and Neogene soils as well as of various Pleistocene glacial deposits, and are of ten covered by residual lags. This type of valley stretch occurs in the vicinity of Dęblin. The surface of the erosion-resistant Holocene alluvial basement averages at 5-7 m below the mean water level. It is exposed on the channel bottom during high-water stages, as seen from a residual layer and from the low density of the contemporary channel deposits above them. The morphology of these elevations influences the pattern of the main stream also during mean-water stages. The trend to flood flow concentrations is also seen in the relief of the floodplain.

Źródło:

Geological Quarterly; 2007, 51, 1; 91-102
1641-7291

Pojawia się w:

Geological Quarterly

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 29.

Tytuł:

Experimental Analysis of Horizontal Turbulence of Flow over Flat and Deformed Beds

Autorzy:

Termini, D.

Powiązania:

https://bibliotekanauki.pl/articles/241285.pdf

Data publikacji:

2015

Wydawca:

Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN

Tematy:

open-channel flow
flow turbulence structure
burst cycle
bed forms
laboratory experiments

Opis:

Laboratory experiments in a straight flume were carried out to examine the evolution of large-scale horizontal turbulent structures under flat-bed and deformed-bed conditions. In this paper, the horizontal turbulence of flow under these conditions is analyzed and compared. The conditioned quadrant method is applied to verify the occurrence of turbulent events. The distributions of horizontal Reynolds shear stress and turbulent kinetic energy are also presented and discussed. Results show the occurrence of an “initial” sequence of horizontal vortices whose average spatial length scales with the channel width. Under deformed-bed conditions, this spatial length does not change.

Źródło:

Archives of Hydro-Engineering and Environmental Mechanics; 2015, 62, 3-4; 77-99
1231-3726

Pojawia się w:

Archives of Hydro-Engineering and Environmental Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 30.

Tytuł:

Exact solution of flow in a composite porous channel

Autorzy:

Singh, Sanjeeva Kumar
Verma, Vineet Kumar

Powiązania:

https://bibliotekanauki.pl/articles/140317.pdf

Data publikacji:

2020

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

composite cylindrical channel
porous medium
permeability variation
Brinkman equation
modified Bessel function

Opis:

This article concerns fully developed laminar flow of a viscous incompressible fluid in a long composite cylindrical channel. Channel consist of three regions. Outer and inner regions are of uniform permeability and mid region is a clear region. Brinkman equation is used as a governing equation of motion in the porous region and Stokes equation is used for the clear fluid region. Analytical expressions for velocity profiles, rate of volume flow and shear stress on the boundaries surface are obtained and exhibited graphically. Effect of permeability variation parameter on the flow characteristics has been discussed.

Źródło:

Archive of Mechanical Engineering; 2020, LXVII, 1; 97-110
0004-0738

Pojawia się w:

Archive of Mechanical Engineering

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 31.

Tytuł:

A turbulence model for 3-d flows with anisotropic structure of turbulence

Autorzy:

Czernuszenko, W.
Rylov, A.

Powiązania:

https://bibliotekanauki.pl/articles/241364.pdf

Data publikacji:

2005

Wydawca:

Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN

Tematy:

3D flow
mathematical model
numerical simulation
open channel flow
turbulence model

Opis:

A new turbulence model for flows in open channels with compound cross-sections is presented. The structure of turbulence in these channels can be anisotropic. This structure is described by the turbulent stress tensor that is presented here as the sum of two tensors, namely, normal and shear stress tensors. The normal and shear turbulent stresses are expressed by the turbulence intensities and the mixing length tensor (MLT), respectively. The turbulence intensities can be learned from measurements or another suitable approaches. One such approach that allows calculating the main component of the normal stresses is presented in the paper. The components of MLT are defined based on a new concept of generic mixing length (GML). The generic mixing length is assumed to depend on both distances; from the nearest wall and from the water surface. To demonstrate how the new model works the basic hydrodynamic equations (parabolic approximation of Reynolds equations) together with the turbulence model are solved. The well-known Patankar and Spalding (1972) algorithm was used when solving these equations. A series of numerical simulations were performed for different components of MLT and different channel geometries.

Źródło:

Archives of Hydro-Engineering and Environmental Mechanics; 2005, 52, 4; 303-320
1231-3726

Pojawia się w:

Archives of Hydro-Engineering and Environmental Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 32.

Tytuł:

The effect of temperature-dependent viscosity and thermal conductivity on velocity and temperature field: an analytical solution using the perturbation technique

Autorzy:

Panahi-Kalus, H.
Ahmadinejad, M.
Moosaie, A.

Powiązania:

https://bibliotekanauki.pl/articles/38610956.pdf

Data publikacji:

2020

Wydawca:

Instytut Podstawowych Problemów Techniki PAN

Tematy:

temperature-dependent material properties
laminar channel flow
anaytical solution
perturbation technique

Opis:

This paper proposes a general form of the perturbation expansion method for the governing equations of viscous flow coupled to the temperature evolution. The effect of the variations of viscosity and thermal conductivity with temperature on the temperature and velocity fields in a steady two-dimensional Couette–Poiseuille flow is examined. The presented analytical solution by the perturbation method is validated against a finite difference solution of the governing equations. The numerical and analytical solutions are in good agreement.

Źródło:

Archives of Mechanics; 2020, 72, 6; 555-576
0373-2029

Pojawia się w:

Archives of Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 33.

Tytuł:

Analysis of controlled molecular dynamic flow in a channel with non-equal inlet and outlet cross-sectional areas

Autorzy:

Najafi, H. R.
Karimian, S. M. H.

Powiązania:

https://bibliotekanauki.pl/articles/279977.pdf

Data publikacji:

2017

Wydawca:

Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej

Tematy:

molecular dynamics
nano-channel
steady flow
non-equal inlet and outlet
pressure

Opis:

Thermo-fluid properties are required for numerical modeling of nano/micro devices. These properties are mostly obtained from the results of molecular dynamics (MD) simulations. Therefore, efforts have been made to develop methods for numerical evaluation of fluid properties such as pressure and velocity. One of the main challenges faced by numerical simulations is to simulate steady molecular flow in channels with non-equal inlet and outlet boundaries. Currently, periodic boundary conditions at the inlet and outlet boundaries are an inevitable condition in many steady flow molecular dynamics simulations. As a result, a nano-channel with different cross sectional areas at the inlet and outlet could not be simulated easily. Here, a method is presented to generate and control steady molecular flow in a nano-channel with different cross sectional areas at the inlet and outlet. The presented method has been applied to a converging-diverging channel, and its performance has been studied through qualitative and quantitative representation of flow properties.

Źródło:

Journal of Theoretical and Applied Mechanics; 2017, 55, 4; 1141-1153
1429-2955

Pojawia się w:

Journal of Theoretical and Applied Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 34.

Tytuł:

Numerical simulation of the micropolar fluid flow and heat transfer in a channel with a shrinking and a stationary wall

Autorzy:

Ali, K.
Ashraf, M.

Powiązania:

https://bibliotekanauki.pl/articles/949324.pdf

Data publikacji:

2014

Wydawca:

Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej

Tematy:

channel flow
shrinking/stationary walls
couple stress
quasi-linearization
Joule heating
viscous dissipation

Opis:

We present the numerical study of hydromagnetic (MHD) flow and heat transfer characte- ristics of a viscous incompressible electrically conducting micropolar fluid in a channel with one wall shrinking and the other at rest in the presence of a transverse applied magnetic field. Different from the classical shooting methodology, we employ a combination of a di- rect and an iterative method (SOR with optimal relaxation parameter) for solving the sparse systems of linear algebraic equations arising from the FD discretization of the linearized self similar nonlinear ODEs. Effects of some physical parameters on the flow and heat transfer are discussed and presented through tables and graphs. The present investigation may be beneficial to the flow and thermal control of polymeric processing.

Źródło:

Journal of Theoretical and Applied Mechanics; 2014, 52, 2; 557-569
1429-2955

Pojawia się w:

Journal of Theoretical and Applied Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 35.

Tytuł:

Heat and mass transfer in a vertical channel flow through a porous medium in the presence of radiation

Autorzy:

Guria, M.

Powiązania:

https://bibliotekanauki.pl/articles/2174211.pdf

Data publikacji:

2022

Wydawca:

Uniwersytet Zielonogórski. Oficyna Wydawnicza

Tematy:

transport masy
promieniowanie
przepuszczalność
mass transfer
permeability
porous medium
periodic suction
radiation

Opis:

An analysis is made of heat and mass transfer in a three dimensional flow between two vertical porous plates through a porous medium. Analytical solutions have been obtained using the perturbation technique. The effect of non-dimensional parameters on velocity, temperature and concentration field are shown graphically. It is seen that the main flow velocity decreases with an increase in both the radiation parameter and Schmidt number but increases with an increase in the thermal Grashoff number, mass Grashoff number as well as the permeability parameter. Variations of the shear stress at the left plate are given in a tabular form. It is seen that the shear stress due to the primary flow at the left plate increases with an increase in the Reynolds number but decrease with an increase in the Schmidt number. With the increase of both the radiation parameter and Reynolds number the temperature decreases. The concentration field also decreases with an increase of the Schmidt number. Variations of mass flux at the left plate are given in tabular form. It is seen that the mass flux at the left plate increases with increase in both Schmidt number or Reynolds number.

Źródło:

International Journal of Applied Mechanics and Engineering; 2022, 27, 3; 63--78
1734-4492
2353-9003

Pojawia się w:

International Journal of Applied Mechanics and Engineering

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 36.

Tytuł:

Gas micro-flow-metering with the in-channel Pt resistors

Autorzy:

Łysko, J. M.
Latecki, B.
Nikodem, M.

Powiązania:

https://bibliotekanauki.pl/articles/308828.pdf

Data publikacji:

2005

Wydawca:

Instytut Łączności - Państwowy Instytut Badawczy

Tematy:

detector
silicon
gas
flow
thermo-conductivity

Opis:

Standard thermo-conductive gas flow meters have the side-channel integrated with the temperature detector and heater coils, both winded around the tube. This design suffers from a high thermal capacity, reduced sensitivity in the lower limit flow range, high thermal inertia, long response time and necessity to amplify electronically the output signal. The newly designed TCD detector can be applied as a precise gas flow meter. To identify the composition of the unknown gas, the TCD unit requires a connection to the separation column, application of the reference channel and highly stable flow rate regulator. To measure flow rates, the same TCD unit requires only one flow channel application, with active resistors inside it, and a definition of the gas type. In this work principles of the TCD design, technology and flow rate sensitivity tests are presented.

Źródło:

Journal of Telecommunications and Information Technology; 2005, 1; 98-100
1509-4553
1899-8852

Pojawia się w:

Journal of Telecommunications and Information Technology

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 37.

Tytuł:

Sterowanie rozdziałem przepływów w sieci kanałów rzecznych
Flow controlling in river channel network

Autorzy:

Markowski, J.

Powiązania:

https://bibliotekanauki.pl/articles/59740.pdf

Data publikacji:

2008

Wydawca:

Polska Akademia Nauk. Stowarzyszenie Infrastruktura i Ekologia Terenów Wiejskich PAN

Tematy:

kanaly rzeczne
kanaly otwarte
siec kanalow
przeplyw wody
przeplyw nieustalony
sterowanie
modele komputerowe

Opis:

W artykule przedstawiono przykład zastosowania modelu komputerowego przepływu w sieci kanałów. Rozwiązania takich zadań dla przepływu stacjonarnego są stosunkowo proste obliczeniowo, nawet dla skomplikowanych schematów geometrycznych. Dlatego skupiono się na rozwiązaniu wybranych wariantów sterowania rozdziałem wód w warunkach przepływu niestacjonarnego. Przyjęty schemat geometryczny sieci nawiązuje do układu kanałów w WWW.
In this paper application of hydrodynamic model of flow in the channel net is presented. The solutions of these tasks for stationary flow are relatively simple even for complicated geometric systems. Therefore the author has focused on the solution of selected variants for no – stationary flow control. The taken geometric schema is similar to Wroclaw Water System.

Źródło:

Infrastruktura i Ekologia Terenów Wiejskich; 2008, 07
1732-5587

Pojawia się w:

Infrastruktura i Ekologia Terenów Wiejskich

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 38.

Tytuł:

Application of variation of the parameters method for micropolar flow in a porous channel

Autorzy:

Güngör, Osman
Arslantürk, Cihat

Powiązania:

https://bibliotekanauki.pl/articles/1839802.pdf

Data publikacji:

2020

Wydawca:

Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej

Tematy:

micropolar flow
porous channel
variation of parameters method
przepływ mikropolarny
metoda zmiany parametrów
kanał porowaty

Opis:

This work devoted to study the injective micropolar flow in a porous channel. The flow is driven by suction or injection on the channel walls, and the micropolar model is used to characterize the working fluid. The governing nonlinear partial differential equations are reduced to the nonlinear ordinary coupled differential equations by using Berman’s similarity transformation. These equations are solved for large mass transfer via variation of parameters method (VPM) which has been used effectively in the solution of nonlinear equations recently. This method has not previously been applied to a problem of micropolar flow. The results of the variation of parameters method are found to be in excellent agreement with the results of the Matlab bvp4c solver (NUM). With this validity, the effects of the some important parameters on the velocity and rotation profile of micropolar flow are discussed in detail. It can be seen that increases in the values N1 and N3 have different results in comparison with N2 increasing.

Źródło:

Journal of Applied Mathematics and Computational Mechanics; 2020, 19, 1; 17-29
2299-9965

Pojawia się w:

Journal of Applied Mathematics and Computational Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 39.

Tytuł:

Application of variation of the parameters method for micropolar flow in a porous channel

Autorzy:

Güngör, Osman
Arslantürk, Cihat

Powiązania:

https://bibliotekanauki.pl/articles/122970.pdf

Data publikacji:

2020

Wydawca:

Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej

Tematy:

micropolar flow
porous channel
variation of parameters method
przepływ mikropolarny
metoda zmiany parametrów
kanał porowaty

Opis:

This work devoted to study the injective micropolar flow in a porous channel. The flow is driven by suction or injection on the channel walls, and the micropolar model is used to characterize the working fluid. The governing nonlinear partial differential equations are reduced to the nonlinear ordinary coupled differential equations by using Berman’s similarity transformation. These equations are solved for large mass transfer via variation of parameters method (VPM) which has been used effectively in the solution of nonlinear equations recently. This method has not previously been applied to a problem of micropolar flow. The results of the variation of parameters method are found to be in excellent agreement with the results of the Matlab bvp4c solver (NUM). With this validity, the effects of the some important parameters on the velocity and rotation profile of micropolar flow are discussed in detail. It can be seen that increases in the values N₁ and N₃ have different results in comparison with N₂ increasing.

Źródło:

Journal of Applied Mathematics and Computational Mechanics; 2020, 19, 1; 17-29
2299-9965

Pojawia się w:

Journal of Applied Mathematics and Computational Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 40.

Tytuł:

Numerical study on two dimensional distribution of streamwise velocity in open channel turbulent flows with secondary current effect

Autorzy:

Mohan, S.
Kundu, S.
Ghoshal, K.
Kumar, J.

Powiązania:

https://bibliotekanauki.pl/articles/38616700.pdf

Data publikacji:

2021

Wydawca:

Instytut Podstawowych Problemów Techniki PAN

Tematy:

velocity distribution
open channel flow
turbulent flow
RANS equations
secondary current
finite difference method

Opis:

For studying mechanism of sediment transport in river flows, open channel flow is a prototype. Flow has always three components of velocity for all types of channel geometry and for a time independent uniform flow along streamwise or main flow direction, all the components of velocity are functions of lateral and vertical coordinates. The present study investigates the two dimensional distribution of streamwise (or longitudinal) velocity starting from the Reynolds averaged Navier–Stokes equation for a turbulent open channel flow which is steady and uniform along the main flow direction. Secondary flows both along the vertically upward direction and along the lateral direction are considered which are also taken as functions of lateral and vertical coordinates. Inclusion of the secondary current brings the effect of dip phenomenon in the model. The resulting second order partial differential equation is solved numerically. The model is validated for all the cross-sectional, transverse and centreline velocity distribution by comparing with existing relevant set of experimental data and also with an existing model. Comparison results show good agreement with data as well as with the previous model proving the efficiency of the model. It is found that the transverse velocity distribution depends on the formation of circular vortex in the cross-sectional plane and becomes periodic as the number of circular vortex increases for increasing aspect ratios.

Źródło:

Archives of Mechanics; 2021, 73, 2; 175-200
0373-2029

Pojawia się w:

Archives of Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 41.

Tytuł:

Modeling of heat transfer and fluid flow in a rectangular channel with an obstacle

Autorzy:

Stryczyński, Mikołaj
Majchrzak, Ewa

Powiązania:

https://bibliotekanauki.pl/articles/1839780.pdf

Data publikacji:

2020

Wydawca:

Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej

Tematy:

channel with an obstacle
Fourier-Kirchhoff equation
Navier-Stokes equations
finite difference method
równanie Fouriera-Kirchhoffa
równania Naviera-Stokesa
metoda różnic skończonych

Opis:

Heat transfer and fluid flow in the rectangular channel with an obstacle are considered. The problem is described by the Fourier-Kirchhoff equation, Navier-Stokes equations and continuity equation supplemented by appropriate boundary and initial conditions. To solve this system of equations the finite difference method with a staggered grid is used. The results of computations obtained using authorial computer program are compared with ANSYS Fluent simulation. Computations are carried out for obstacles of various sizes and positions, and on this basis the conclusions are formulated.

Źródło:

Journal of Applied Mathematics and Computational Mechanics; 2020, 19, 2; 121-132
2299-9965

Pojawia się w:

Journal of Applied Mathematics and Computational Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 42.

Tytuł:

Instability of viscous incompressible flow in a channel with transversely corrugated walls
Zjawisko destabilizacji przepływu laminarnego w kanale z poprzecznie pofalowanymi ścianami

Autorzy:

Szumbarski, J.

Powiązania:

https://bibliotekanauki.pl/articles/279211.pdf

Data publikacji:

2007

Wydawca:

Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej

Tematy:

wavy channel
laminar flow
linear stability

Opis:

Destabilization of the laminar flow in a channel with transversly wavy walls is investigated. The basic flow is determined by a semi-analytical method based on the concept of immersed boundaries. The stability equations are discretized by the spectrally accurate Chebyshev-tau method. It is demonstrated that the transversal wall waviness can be used in order to achieve destabilization of the laminar flow at low Reynolds numbers. Possible applications include the improvement of mixing and heat/mass transfer in various devices used in heat technology, biotechnology and medicine.
Praca poświęcona jest zjawisku destabilizacji przepływu laminarnego w kanale wywołanej poprzecznym pofalowaniem ścian. Przepływ niezaburzony wyznaczono przy pomocy semi-analitycznej metody zanurzonych granic. Wyprowadzono równania stateczności, które następnie poddano dyskretyzacji przy użyciu wielomianów Czebyszewa. Pokazano, że poprzeczne pofalowanie ścian o odpowiedniej geometrii prowadzi do destabilizacji przepływu przy niskich liczbach Reynoldsa i omówiono własności pola zaburzeń. Wydaje się, że opisany efekt może mieć znaczenie dla intensyfikacji mieszania i poprawy efektywności procesów transportu w technice cieplnej, biotechnologii i medycynie.

Źródło:

Journal of Theoretical and Applied Mechanics; 2007, 45, 3; 659-683
1429-2955

Pojawia się w:

Journal of Theoretical and Applied Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 43.

Tytuł:

LES of turbulent channel flow and heavy particle dispersion
Zastosowanie metody dużych wirów do przepływu turbulentnego w kanale i dyspersji cząstek

Autorzy:

Pozorski, J.
Wacławczyk, T.
Łuniewski, M.

Powiązania:

https://bibliotekanauki.pl/articles/279209.pdf

Data publikacji:

2007

Wydawca:

Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej

Tematy:

turbulent flow
large eddy simulation
particle dispersion

Opis:

The Eulerian-Lagrangian approach has been applied to two-phase turbulent flows with dispersed heavy particles. First, numerical computations of the continuous phase (fluid) have been performed using the Direct Numerical Simulations (DNS) and Large-Eddy Simulations (LES) for the case of a fully-developed channel flow. Parallelisation efficiency of flow and particle solvers has been estimated. Residual turbulent kinetic energy has been found from filtered DNS (also called a priori LES); a model for this quantity has been assessed. Then, heavy particles have been tracked in the LES velocity field. Statistics of particle motion (mean velocity, intensity of velocity fluctuations) and the profile of cross-stream number density as well as preliminary results for particle wall deposition have been obtained.
W pracy zastosowano podejście Eulera-Lagrange'a do wyznaczenia ruchu fazy dyspersyjnej (cząstki, krople) w turbulentnym przepływie dwufazowym. Obliczenia ruchu fazy ciągłej (płynu) przeprowadzono za pomocą rozwiązania pełnych równań przepływu (DNS) oraz przy użyciu metody dużych wirów (LES) dla przypadku rozwiniętego przepływu w kanale płaskim. Oszacowano efektywność zrównoleglenia obliczeń numerycznych. Określono poziom energii kinetycznej skal podsiatkowych; porównano ją z wynikami uzyskanymi z modelu dynamicznego. Wyznaczono trajektorie cząstek fazy dyspersyjnej w polu prędkości LES. Określono statystyki ich ruchu: prędkość średnią, intensywność fluktuacji prędkości, profil koncentracji cząstek w poprzek kanału; uzyskano wstępne wyniki dla separacji cząstek na ściankach.

Źródło:

Journal of Theoretical and Applied Mechanics; 2007, 45, 3; 643-657
1429-2955

Pojawia się w:

Journal of Theoretical and Applied Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 44.

Tytuł:

Transient flow through a porous channel with ramped pressure gradient and velocity slip boundary condition

Autorzy:

Jha, Basant K.
Yunus, Zainab Sa'id

Powiązania:

https://bibliotekanauki.pl/articles/2174168.pdf

Data publikacji:

2022

Wydawca:

Uniwersytet Zielonogórski. Oficyna Wydawnicza

Tematy:

przepływ przejściowy
prędkość
ciśnienie
transient flow
velocity slip
ramped pressure gradient
Riemann-Sum approximation technique

Opis:

A transient flow formation of an incompressible fluid through a horizontal porous channel assuming a ramped pressure gradient is considered with the velocity slip boundary conditions. The flow is a laminar flow caused by ramped pressure gradient along the flow direction. The equation governing the flow is modeled, and solved by the Laplace transformation technique to obtain a semi-analytical solution under slip boundary conditions. It was noted that the flow velocity increases as the slip parameter is increased.

Źródło:

International Journal of Applied Mechanics and Engineering; 2022, 27, 1; 78--90
1734-4492
2353-9003

Pojawia się w:

International Journal of Applied Mechanics and Engineering

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 45.

Tytuł:

Impact of transversely-oriented wall corrugation on hydraulic resistance of a channel flow
Wpływ poprzecznego pofalowania ścian na opory hydrauliczne przepływu w kanale

Autorzy:

Szumbarski, J.
Blonski, S.
Kowalewski, T. A.

Powiązania:

https://bibliotekanauki.pl/articles/139979.pdf

Data publikacji:

2011

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

przepływ w kanale
opory hydrauliczne
ściany pofalowane
metody numeryczne
channel flow
hydraulic resistance
corrugated walls
numerical methods

Opis:

The impact of the transversely-oriented sinusoidal wall corrugation on the hydraulic drag is investigated numerically for the flow through the channel of finite width and with flat sidewalls. The numerical method, based on the domain transformation and Chebyshev-Galerkin discretization, is used to investigate the flow resistance of the laminar, parallel and pressure-driven flow. The obtained results are compared to the reference case, i.e., to the flow through the channel with rectangular cross section of the same aspect ratio. Simple explanation of the gain in the volumetric flow rate observed in the flow through spanwise-periodic channel with long-wave transversely-oriented wall corrugation is provided. In the further analysis, pressure drop in the flows with larger Reynolds numbers are studied numerically by means of the finite-volume commercial package Fluent. Preliminary experimental results confirm the predicted tendency.
Przedmiotem artykułu jest analiza numeryczna wpływu poprzecznego sinusoidalnego pofalowania ścian na opory hydrauliczne przepływu cieczy lepkiej w kanale. Do wyznaczenia stacjonarnego pola ruchu cieczy lepkiej w kanale posłużono się transformacją obszaru i spektralną metodą Czebyszewa-Galerkina. Obliczone wartości strat ciśnienia porównano z przepływem laminarnym w kanale o ścianach płaskich i przekroju prostokątnym, przy zachowaniu takiej samej wartości stosunku szerokości kanału do jego wysokości. Podano objaśnienie efektu zmiejszenia oporów hydraulicznych w przypadku poprzecznego pofalowania o dużej długości fali. Omówiono również wyniki analizy wpływu pofalowania ścian na straty ciśnienia dla przepływów z większymi liczbami Reynoldsa, uzyskane przy pomocy komercyjnego programu Fluent. Przedstawiono wstępne wyniki badań eksperymentalnych, które potwierdzają zależności otrzymane w modelach numerycznych.

Źródło:

Archive of Mechanical Engineering; 2011, LVIII, 4; 441-466
0004-0738

Pojawia się w:

Archive of Mechanical Engineering

Dostawca treści:

Biblioteka Nauki

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Skocz do pozycji: 46.

Tytuł:

Rozkłady prędkości wody w korytach z elementami sprężystymi
Description of the water velocity profiles in open channel flow through submerged flexible stems

Autorzy:

Kubrak, E.
Wielgosz, P.

Powiązania:

https://bibliotekanauki.pl/articles/886377.pdf

Data publikacji:

2008

Wydawca:

Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Wydawnictwo Szkoły Głównej Gospodarstwa Wiejskiego w Warszawie

Tematy:

dno rzeczne
elementy sprezyste
gestosc elementow sprezystych
inzynieria wodna
koryta rzeczne
modele matematyczne
predkosc przeplywu
przeplyw wody
rozklad predkosci przeplywu

Opis:

The water flow velocities in open channel through submerged flexible stems calculated using stationary uniform flow equation are presented. The cantilever beam theory is used to compute the defl ection of the flexible stem. The turbulent shear stresses were calculated using Boussinesqu equation. In order to relate turbulent stresses to velocity gradients mixing length theory was used (Kubrak E. 2006, 2007). The new numerical scheme is appropriate for analysis of the vertical velocity profile through submerged flexible stems for given bottom roughness. Distributions of the water flow velocity in open channels with stems density, diameters of the stem and channel slope are given. Mean velocities and their regression equations for the layer with stems, above stems and cross section of the channel are given.

Źródło:

Scientific Review Engineering and Environmental Sciences; 2008, 17, 3[41]
1732-9353

Pojawia się w:

Scientific Review Engineering and Environmental Sciences

Dostawca treści:

Biblioteka Nauki

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Skocz do pozycji: 47.

Tytuł:

Numerical solution of MHD channel flow in a porous medium with uniform suction and injection in the presence of an inclined magnetic field

Autorzy:

Chutia, Muhim

Powiązania:

https://bibliotekanauki.pl/articles/2175529.pdf

Data publikacji:

2022

Wydawca:

Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej

Tematy:

MHD flow
Brinkman equation
permeability parameter
Hartmann number
uniform suction and injection
finite difference method
przepływ MHD
równanie Brinkmana
parametr przepuszczalności
liczba Hartmanna
równomierne ssanie i wtrysk
metoda różnic skończonych

Opis:

In this paper, the steady fully developed MHD flow of a viscous incompressible electrically conducting fluid through a channel filled with a porous medium and bounded by two infinite walls is investigated numerically for the cases (i) Poiseuille flow and (ii) Couette-Poiseuille flow; with uniform suction and injection at the walls in the presence of an inclined magnetic field. The Brinkman equation is used for the flow in the porous channel and solved numerically using the finite difference method. Numerical results are obtained for velocity. The effects of various dimensionless parameters such as Hartmann number (M), suction/injection parameter (S), permeability parameter (α) and angle of inclination (θ) on the flow are discussed and presented graphically.

Źródło:

Journal of Applied Mathematics and Computational Mechanics; 2022, 21, 2; 5--13
2299-9965

Pojawia się w:

Journal of Applied Mathematics and Computational Mechanics

Dostawca treści:

Biblioteka Nauki

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Skocz do pozycji: 48.

Tytuł:

Opór hydrauliczny przy przepływie gaz - ciecz kanałem z wypełnieniem siatkowym
Hydraulic drag in gas - liquid flow through a channel with the wire mesh packing

Autorzy:

Dyga, R.

Powiązania:

https://bibliotekanauki.pl/articles/2070757.pdf

Data publikacji:

2009

Wydawca:

Stowarzyszenie Inżynierów i Techników Mechaników Polskich

Tematy:

wypełnienie siatkowe
przepływ gaz-ciecz
opór przepływu
gas-liquid flow
pressure drop

Opis:

W pracy opisano analizę wyników badań doświadczalnych dotyczących strat ciśnienia przy przepływie jedno i dwufazowym gaz — ciecz przez kanały z wypełnieniem siatkowym. Przedstawiono rezultaty wykorzystania wybranych modeli hydrauliki przepływu dwufazowego przez wypełnienia porowate do opisu przepływu gaz-ciecz przez strukturę siatkową.
Analysis of experimental study results concerning pressure drop in single and two-phase gas — liquid flow through wire mesh packing channels is presented in the paper. The results of application of selected hydraulic models of two-phase flow through a porous packing in description of gas - liquid flow through the meshed structure are presented.

Źródło:

Inżynieria i Aparatura Chemiczna; 2009, 6; 49-50
0368-0827

Pojawia się w:

Inżynieria i Aparatura Chemiczna

Dostawca treści:

Biblioteka Nauki

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Skocz do pozycji: 49.

Tytuł:

Koncepcja stanowiska do badania wypływu zanieczyszczeń z kanałów burzowych
Concept of an experimental stand for study the outflow of pollutants from combined sewer overflows

Autorzy:

Rząsa, M. R.
Boguniewicz-Zabłocka, J.

Powiązania:

https://bibliotekanauki.pl/articles/268350.pdf

Data publikacji:

2015

Wydawca:

Politechnika Gdańska. Wydział Elektrotechniki i Automatyki

Tematy:

przepływ w kanale otwartym
przepływ dwufazowy
komputerowa analiza obrazu
open channel flow
two-phase flow
computer image processing

Opis:

Pomiary przepływu mieszaniny polidyspersyjnej są jednymi z najtrudniejszych do zrealizowania w warunkach technicznych. W artykule opisano koncepcję systemu pomiarowego, który umożliwi obserwację przepływającej mieszaniny oraz wyznaczenia podstawowych parametrów jej ruchu. W pracy zaproponowano sposób opisu wydmy przesuwającego się piasku. Wymiary wydmy zdefiniowano za pomocą czterech charakterystycznych wymiarów. Zaproponowano stanowisko laboratoryjne umożliwiające badanie przepływu mieszaniny w kanale otwartym przy różnym nachyleniu kanału i różnym składzie granulometrycznym frakcji stałej. Stanowisko wyposażono w system rejestracji obrazu. Obrazy zarejestrowane kamerą poddawane są procesowi komputerowej analizy obrazu i na tej podstawie możliwe jest określenie podstawowych parametrów ruchu mieszaniny. Praca zawiera opis koncepcji stanowiska laboratoryjnego oraz ideę metody analizy obrazu.
A storm water system with open channels for the discharge of rainwater exists in most urbanised areas. The flow in these kind of channels is generally multiphase flow, in which there are solids and liquids and in some places there may be an additional gas phase. Therefore the ability to describe such flow is reduces to the description of the motion of the polydisperse mixture. Polydisperse mixture flow measurements are among the most difficult to achieve in technical terms. The article describes the concept of a measurement system that allows observation of the poly-dispersed flow and determine the basic parameters of its motion. Concept of experimental laboratory set-up was proposed to measure the parameters of the polydispersed mixture flow process in open channel with different slope of the channel and various granulometry of the solid fraction. In this work description of sand dunes with four typical parameters was proposed. A digital camera is used to interrogate the flow. Images recorded on the camera will be subjected to a process of image analysis, and from this the basic parameters of the movement are determined. The work includes a description of the experimental set-up with the idea of image analysis methods.

Źródło:

Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej; 2015, 47; 155-158
1425-5766
2353-1290

Pojawia się w:

Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej

Dostawca treści:

Biblioteka Nauki

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Skocz do pozycji: 50.

Tytuł:

Opis rozkładu prędkości przepływu wody w korycie z elementami sprężystymi
Description of the water velocity profiles in open channel flow through submerged flexible stems

Autorzy:

Kubrak, E.

Powiązania:

https://bibliotekanauki.pl/articles/886535.pdf

Data publikacji:

2006

Wydawca:

Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Wydawnictwo Szkoły Głównej Gospodarstwa Wiejskiego w Warszawie

Tematy:

koryta rzeczne
dno rzeczne
elementy sprezyste
przeplyw wody
predkosc przeplywu
rozklad predkosci przeplywu

Źródło:

Scientific Review Engineering and Environmental Sciences; 2006, 15, 2[34]
1732-9353

Pojawia się w:

Scientific Review Engineering and Environmental Sciences

Dostawca treści:

Biblioteka Nauki

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