Wszystkie pola: flow Channel - Katalog OPAC zbiorów

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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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