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Wyświetlanie 1-15 z 19
Tytuł:
Boundary problem for equations of steady gradually varied flow in open channels
Autorzy:
Szymkiewicz, R.
Powiązania:
https://bibliotekanauki.pl/articles/241107.pdf
Data publikacji:
2001
Wydawca:
Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
Tematy:
differential equations
steady flow
gradually varied flow
open channels
Opis:
In this paper the problem of solution of ordinary differential equations describing a steady, gradually varied flow is discussed. It is shown that, apart from the initial problem usually solved for open channels, the formulation of the boundary problem is necessary when water levels are imposed at ends of channel. This approach is the mathematically correct formulation of the solution problem for steady, gradually varied flow equations. It enables us to determine directly the water profile and discharge for a single channel, as well as for channel network, instead of the trial and error method usually used. Moreover the formulation of boundary problem with respect to the Manning coefficient and lateral inflow is presented. To solve the listed problems the finite differences method is used.
Źródło:
Archives of Hydro-Engineering and Environmental Mechanics; 2001, 48, 4; 23-37
1231-3726
Pojawia się w:
Archives of Hydro-Engineering and Environmental Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
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
Artykuł
Tytuł:
Investigation of powder properties using alternating strain paths
Autorzy:
Morgeneyer, M.
Schwedes, J.
Powiązania:
https://bibliotekanauki.pl/articles/1955773.pdf
Data publikacji:
2003
Wydawca:
Politechnika Gdańska
Tematy:
powder
biaxial shear tester
steady flow
precompaction strain path
Opis:
Steady-state flow (ssf) of powders has been investigated using alternating strain paths, with precompacted powder samples sheared in alternating directions. The dependency of ssf on the level of precompaction is shown.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2003, 7, 4; 571-578
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of Average Energy Slope Estimation Formulas for One-dimensional Steady Gradually Varied Flow
Autorzy:
Artichowicz, W.
Mikos-Studnicka, P.
Powiązania:
https://bibliotekanauki.pl/articles/241083.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
Tematy:
open channel
steady flow
gradually varied flow
standard step method
energy slope
Opis:
To find the steady flow water surface profile, it is possible to use Bernoulli’s equation, which is a discrete form of the differential energy equation. Such an approach requires the average energy slope between cross-sections to be estimated. In the literature, many methods are proposed for estimating the average energy slope in this case, such as the arithmetic mean, resulting in the standard step method, the harmonic mean and the geometric mean. Also hydraulic averaging by means of conveyance is commonly used. In this study, water surface profiles numerically computed using different formulas for expressing the average slope were compared with exact analytical solutions of the differential energy equation. Maximum relative and mean square errors between numerical and analytical solutions were used as measures of the quality of numerical models. Experiments showed that all methods gave solutions useful for practical engineering purposes. For every method, the numerical solution was very close to the analytical one. However, from the numerical viewpoint, the differences between the methods were significant, as the errors differed up to two orders of magnitude.
Źródło:
Archives of Hydro-Engineering and Environmental Mechanics; 2014, 61, 3-4; 89--109
1231-3726
Pojawia się w:
Archives of Hydro-Engineering and Environmental Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical Calculations with a Multi-layer Model of Mixed Sand Transport Against Measurements in Wave Motion and Steady Flow
Autorzy:
Kaczmarek, Leszek M.
Radosz, Iwona
Zawisza, Jerzy
Powiązania:
https://bibliotekanauki.pl/articles/2069944.pdf
Data publikacji:
2021
Wydawca:
Politechnika Koszalińska. Wydawnictwo Uczelniane
Tematy:
wave motion
steady flow
sediment transport
transport
wave trough
wave crest
Opis:
A multi-layer model is used to calculate time-dependent sediment velocity and concentration vertical profiles. This model, in which the differences in sediment transport at different distances from the bed are considered is intended both for the wave motion and steady flow. Numerical calculations were carried out for sediment transport during the wave crest and trough and total sediment transport as a sum of their absolute values. The model concept of variation in shear stress from the skin stress value above the bed to the stress value at the bed previously proposed for steady flow is extended here for the wave motion and verified by direct stress measurements. The calculations were carried out for mixed sand sediments with different grain size distributions including semi-uniform and poorly sorted grains. Comparison with the available small- and large -scale data from flumes and oscillating tunnels yields agreement typically within plus/minus a factor two of measurements.
Źródło:
Rocznik Ochrona Środowiska; 2021, 23; 629--641
1506-218X
Pojawia się w:
Rocznik Ochrona Środowiska
Dostawca treści:
Biblioteka Nauki
Artykuł
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
Artykuł
Tytuł:
Computational fluid dynamics methods in turbomachinery
Autorzy:
Chmielniak, T. J.
Powiązania:
https://bibliotekanauki.pl/articles/1953985.pdf
Data publikacji:
1998
Wydawca:
Politechnika Gdańska
Tematy:
computational fluid dynamics CFD
CFD
turbomachinery
numerical methods
modelling
steady flow
unsteady flow
multiphase flow
multicomponent flow
blade cooling
Opis:
This paper aims to present a general view of flow problems in turbomachinery and the current levels of numerical methods for solving these problems. The flow models used for modelling phenomena in blade cascades are presented. Models of turbulence are discussed. A variety of examples of turbomachinery problems, such as steady, unsteady, multiphase and multicomponent flows, and also blade cooling are described. The actual research fields of computational fluid mechanics are presented.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 1998, 2, 2; 205-213
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comprehensive circumscribing of non-linearity cases of a water supply system with smooth flow control
Autorzy:
Orłowski, R.
Powiązania:
https://bibliotekanauki.pl/articles/241404.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
Tematy:
flow reducing valve
non-linearity of system
pressure reducing valve
steady flow
variable frequency drives
water supply system
Opis:
The descriptions found in the literature, of cases of even relatively strong non-linearity of the water supply systems, as well as their mathematical treatment, are rare and incomplete. They refer mainly to the non-linearity with respect to smooth flow control components (for instance, to the operation of pressure reducing valves (PRV), flow reducing valves (FRV) and pumps with motors equipped with smooth rotational speed control - variable frequency drives (VFD)). The article proposes a formally correct method of a comprehensive solution of the above non-linearity cases based on successive simulations with some dynamic analysis of the sensitivity of the system to the operation of the smooth control components mentioned. An appropriate algorithm controlling the effectiveness of the calculations secures correct description of the behaviour of the system for an arbitrary, in practice, method of control of flows, even if all the proposed smooth control methods are used simultaneously. The effects of the use of the solutions presented in mathematical modelling are illustrated by selected results of simulation carried out for an existing water supply system.
Źródło:
Archives of Hydro-Engineering and Environmental Mechanics; 2006, 53, 1; 7-30
1231-3726
Pojawia się w:
Archives of Hydro-Engineering and Environmental Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Heat transfer study from square cylinder immersed in water-based nanofluid: Effect of orientation
Autorzy:
Kaur, Jaspinder
Ratar, Jatinder Kumar
Tiwari, Anurag Kumar
Powiązania:
https://bibliotekanauki.pl/articles/2173435.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
inclined square cylinder
nanofluids
Reynolds number
Prandtl number
steady flow
regime
nanopłyn
liczba Reynoldsa
liczba Prandtla
przepływ stały
Opis:
Heat transfer study from the heated square cylinder at a different orientation angle to the stream of nanofluids has been investigated numerically. CuO-based nanofluids were used to elucidate the significant effect of parameters: Reynolds number (1–40), nanoparticle volume fraction (0.00–0.05), the diameter of the NPs (30–100 mn) and the orientation of square cylinder (0–90). The numerical results were expressed in terms of isotherm contours and average Nusselt number to explain the effect of relevant parameters. Over the range of conditions, the separation of the boundary layers of nanofluids increased with the size of the NPs as compared to pure water. NPs volume fraction and its size had a significant effect on heat transfer rate. The square cylinder of orientation angle (45) gained a more efficient heat transfer cylinder than other orientation angles. Finally, the correlations were developed for the average Nusselt number in terms of the relevant parameters for 45 orientation of the cylinder for new applications.
Źródło:
Chemical and Process Engineering; 2022, 43, 2; 243--250
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of maintenance of floodplains of the Vistula River on high water levels on the section from Włocławek to Toruń
Wpływ stanu utrzymania terenów zalewowych Wisły na poziomy wysokich wód na odcinku od Włocławka do Torunia
Autorzy:
Gąsiorowski, D.
Szydłowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/397545.pdf
Data publikacji:
2013
Wydawca:
ENERGA
Tematy:
floodplain inundation
gradually varied steady flow
flow capacity of the river
mathematical modeling
zatopienie terenu zalewowego
przepływ ustalony wolnozmienny
przepustowość rzeki
modelowanie matematyczne
Opis:
This article describes the methodology of hydraulic calculations to estimate the water levels in open channels for steady gradually varied flow. The presented method has been used to analyse the water level on the Vistula River from Włocławek cross-section to Toruń cross-section. The HEC-RAS modelling system has been used for parameterization of the river channel and flood¬plains, as well as for flow simulation. The results obtained have been the basis for assessing the impact of maintenance of floodplains on water level during maximum discharges.
W artykule opisano metodykę obliczeń hydraulicznych umożliwiających wyznaczenie układu zwierciadła wody w korytach otwartych w warunkach wolnozmiennego przepływu ustalonego. Wybraną metodę wykorzystano do analizy układu zwierciadła wody w rzece Wiśle na odcinku od przekroju Włocławek do przekroju Toruń. Do parametryzacji koryta i terenów zalewowych rzeki, jak również do symulacji przepływu, wykorzystano program obliczeniowy HEC-RAS. Na podstawie uzyskanych wyników oceniono wpływ stanu utrzymania terenów zalewowych na położenie zwierciadła w trakcie występowania przepływów maksymalnych.
Źródło:
Acta Energetica; 2013, 3; 112-120
2300-3022
Pojawia się w:
Acta Energetica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ranges of Backwater Curves in Lower Odra
Zasięgi krzywej spiętrzenia dolnej Odry
Autorzy:
Mańko, R.
Powiązania:
https://bibliotekanauki.pl/articles/396723.pdf
Data publikacji:
2018
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
backwater curves
steady flow
the mouth of the Odra River
Bernoulli equation
krzywe spiętrzenia
ruch ustalony jednostajny
ujście Odry
równanie Bernoulliego
Opis:
In the paper, the backwater curve ranges at the mouth of the Odra River with changing boundary conditions were analysed. The aim of the study is to determine which boundary condition, i.e. stage of lower cross-section or flow in upper cross-section, has a greater impact on the formation of the backwater curve at the mouth of the Odra River. Due to the complicated system of the Lower Odra River network (Międzyodrze and Dabie Lake), the analysis takes into consideration a section of the Odra River from a weir in Widuchowa upwards, thereby accepting as an axiom that the cross-section in Widuchowa is within the range of sea impact, regardless of other hydrological conditions.
W pracy poddano analizie zasięgi krzywych spiętrzenia w ujściowym odcinku Odry przy zmiennych warunkach brzegowych. Celem pracy jest określenie, który warunek brzegowy tj. napełnienie stanowiska dolnego czy wartość przepływu w rzece ma większy wpływ na formowanie się krzywej spiętrzenia w ujściowym odcinku Odry. Ze względu na skomplikowany układ sieci rzecznej dolnej Odry (tj. Międzyodrze i jezioro Dąbie) do analizy przyjęto odcinek Odry od jazu w Widuchowej w górę koryta, zarazem przyjmując w obliczeniach, że stany wody w przekroju Widuchowa determinowane są wyłącznie stanami morza.
Źródło:
Civil and Environmental Engineering Reports; 2018, No. 28(4); 25-35
2080-5187
2450-8594
Pojawia się w:
Civil and Environmental Engineering Reports
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The pollutant transport equation for a steady, gradually varied flow in an open channel network: a solution of high accuracy
Autorzy:
Szymkiewicz, R.
Powiązania:
https://bibliotekanauki.pl/articles/1933160.pdf
Data publikacji:
2007
Wydawca:
Politechnika Gdańska
Tematy:
steady gradually varied flow
advection-diffusion equation
splitting technique
integral of convolution
Opis:
The paper is concerned with solving the transport pollutant problem for a steady, gradually varied flow in an open channel network. The 1D advective-diffusive transport equation is solved using the splitting technique. An analytical solution of the linear advective-diffusive equation in the form of an impulse response function is used to solve the advection-diffusion part of the governing equation. This approach, previously applied in solutions of the advection-diffusion equation for a single channel, is extended to a channel network. Numerical calculations are only required to compute the integral of convolution. The finite difference method is used to solve the second part of the governing equation, containing the source term. The applied approach has considerable advantages, especially appreciable in the case of advection-dominated transport with large gradients of concentration, since it generates no numerical dissipation or dispersion. The flow parameters are obtained via solution of the steady, gradually varied flow equation. In the final non-linear system of algebraic equations obtained through approximation of the ordinary differential equation, the depths at each cross-section of channels and the discharge at each branch of the network are considered as unknowns. The system is solved using the modified Picard iteration, which ensures convergence of the iterative process for a steady, gradually varied flow solved for both looped and tree-type open channel networks.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2007, 11, 4; 365-382
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Unsteady/steady natural convection flow of reactive viscous fluid in a vertical annulus
Autorzy:
Jha, B. K.
Samaila, A. K.
Ajibade, A. O.
Powiązania:
https://bibliotekanauki.pl/articles/265663.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
konwekcja naturalna
lepki płyn
egzotermiczna otulina
unsteady/steady natural convection flow
reactive viscous fluid
exothermic
open ended vertical annulus
Opis:
This paper presents both analytical and numerical analyses of a fully developed unsteady/steady natural convection flow of a reactive viscous fluid in an open ended vertical annulus. Analytical expressions for velocity, temperature, skin-friction and rate of heat transfer are obtained after simplifying and solving the governing differential equations with reasonable approximations. The interesting result found in this study is that an increase in non-dimensional time (t) , increases both temperature and velocity profiles until a steady-state value is attained. Subsequent results obtained by numerical calculations show excellent agreement with analytical results.
Źródło:
International Journal of Applied Mechanics and Engineering; 2013, 18, 1; 73-83
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of Energy Slope Averaging Methods on Numerical Solution of 1D Steady Gradually Varied Flow
Autorzy:
Artichowicz, W.
Prybytak, D.
Powiązania:
https://bibliotekanauki.pl/articles/240952.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
Tematy:
standard step method
numerical integration
initial-value problem
ordinary differential equation
open channel
steady gradually varied flow
energy slope
Opis:
In this paper, energy slope averaging in the one-dimensional steady gradually varied flow model is considered. For this purpose, different methods of averaging the energy slope between cross-sections are used. The most popular are arithmetic, geometric, harmonic and hydraulic means. However, from the formal viewpoint, the application of different averaging formulas results in different numerical integration formulas. This study examines the basic properties of numerical methods resulting from different types of averaging.
Źródło:
Archives of Hydro-Engineering and Environmental Mechanics; 2015, 62, 3-4; 101-119
1231-3726
Pojawia się w:
Archives of Hydro-Engineering and Environmental Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative assesment of steady-state pipeline gas flow models
Analiza porównawcza modeli przepływu gazu w rurociągu w stanach ustalonych
Autorzy:
Chaczykowski, M.
Osiadacz, A.
Powiązania:
https://bibliotekanauki.pl/articles/963887.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
pipeline gas flow
steady-state flow model
convective term
kinetic energy term
design flow equation
GERG 2004 application
transport rurociągowy
ustalony przepływ gazu
człon konwekcyjny
człon energii kinetycznej
równanie przepływu
metoda GERG 2004
Opis:
One-dimensional, non-isothermal flow of gas in a straight pipe has been considered to predict pressure and temperature profiles along the horizontal pipeline under steady-state conditions. Selected analytical models for the simplified calculation of these profiles are evaluated on the basis of the numerical solution of the accurate model, which incorporates the convective term in the momentum equation and the kinetic energy term in the energy equation, while treating the enthalpy as a function of pressure and temperature. For closure of the system of the conservation equations, the GERG 2004 equation of state was chosen. In order to present the discrepancies introduced by the models, the results of the numerical and analytical solutions are compared with the field data. The results show that in the case of the high pressure gas transmission system, the effects of the convective term in the momentum equation and the kinetic energy term in the energy equation are negligible for pipeline pressure and temperature calculation accuracies. It also indicates that real gas effects play an important role in the temperature distribution along the pipeline and cannot be neglected from the calculation when approximate analytical equations are used.
W artykule analizowano jednowymiarowy, nieizotermiczny przepływ gazu w stanie ustalonym w celu określenia zmian ciśnienia i temperatury w poziomym gazociągu. Wyniki uproszczonych obliczeń za pomocą wybranych modeli analitycznych zostały porównane z wynikami obliczeń uzyskanych za pomocą numerycznego całkowania modelu dokładnego, zawierającego człon konwekcyjny w równaniu pędu oraz człon energii kinetycznej w równaniu energii, jednocześnie przyjmując entalpię jako funkcję ciśnienia i temperatury. W celu zamknięcia układu równań zachowania zastosowano równanie stanu zgodnie z metodą GERG 2004. Dla przedstawienia niedokładności związanych z zastosowaniem różnych modeli, przeprowadzono weryfikację wyników na zbiorze danych rzeczywistych. Wyniki pokazują, że w przypadku systemów przesyłowych wysokiego ciśnienia, wpływ członu konwekcyjnego w równaniu pędu oraz członu energii kinetycznej w równaniu energii jest pomijalny z punktu widzenia dokładności obliczeń wartości ciśnienia i temperatury w gazociągu. Ponadto, wyniki pokazują, że prawidłowy opis właściwości gazu rzeczywistego odgrywa ważną rolę w obliczeniach zmian temperatury wzdłuż gazociągu i powinien być stosowany w przypadku przybliżonych metod analitycznych.
Źródło:
Archives of Mining Sciences; 2012, 57, 1; 23-38
0860-7001
Pojawia się w:
Archives of Mining Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
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