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Tytuł:
A Comparison of Simplified Two-dimensional Flow Models Exemplified by Water Flow in a Cavern
Autorzy:
Prybytak, D.
Zima, P.
Powiązania:
https://bibliotekanauki.pl/articles/241287.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
Tematy:
potential flow
Stokes flow
Navier-Stokes flow
BEM
OpenFOAM
Opis:
The paper shows the results of a comparison of simplified models describing a two-dimensional water flow in the example of a water flow through a straight channel sector with a cavern. The following models were tested: the two-dimensional potential flow model, the Stokes model and the Navier-Stokes model. In order to solve the first two, the boundary element method was employed, whereas to solve the Navier-Stokes equations, the open-source code library OpenFOAM was applied. The results of numerical solutions were compared with the results of measurements carried out on a test stand in a hydraulic laboratory. The measurements were taken with an ADV probe (Acoustic Doppler Velocimeter). Finally, differences between the results obtained from the mathematical models and the results of laboratory measurements were analysed.
Źródło:
Archives of Hydro-Engineering and Environmental Mechanics; 2017, 64, 3-4; 141-154
1231-3726
Pojawia się w:
Archives of Hydro-Engineering and Environmental Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the magnetization-based Lagrangian methods for 2D and 3D viscous flows. Part 2 - numerical implementation and results
Langrangeowska metoda magnetyzacji dla dwu i trójwymiarowych ruchów płynu lepkiego. Część II - realizacja numeryczna i wyniki
Autorzy:
Duszyński, P.
Olszewski, P.
Poćwierz, M.
Styczek, A.
Szumbarski, J.
Powiązania:
https://bibliotekanauki.pl/articles/281273.pdf
Data publikacji:
2002
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
viscous flow
Navier-Stokes equations
magnetization
stretching
Opis:
The numerical implementation of the Lagrangian method using particles of the magnetization field (magnetons) has been considered. A detailed description of essential elements of the algorithm has been provided. The presentation has focused on computations of stretching, where a novel integral-based rather than point wise approach has been proposed. The results of test computations, carried out for viscous flows past 2D and 3D bodies, have been presented. Difficulties with obtaining stable large-time simulations have been encountered and discussed. It has also been shown that, in contrast to flows around solid bodies, the vortex dynamics in the absence of boundaries can be successfully simulated, however, some consistent remeshing technique may by necessary to achieve appropriate resolution.
W tej części pracy przedstawiono realizację numeryczną i opis wyników wyznaczania ruchów cieczy lepkiej uzyskanych lagrangeowską metodą cząstek magnetyzacji. Podano szczegóły wyznaczenia członu źródłowego (tzw.stretching term). Zaproponowano szczególny nowy sposób postępowania związany z tym efektem. Praca zawiera wyniki symulacji opływów dwu i trójwymiarowych oraz dyskusję napotkanych trudności. Podano też wyniki symulacji ewolucji swobodnych struktur wirowych. Modelowanie takich struktur jest prostsze wobec braku warunku brzegowego.
Źródło:
Journal of Theoretical and Applied Mechanics; 2002, 40, 4; 825-846
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the magnetization-based Lagrangian methods for 2D and 3D viscous flows. Part 1 - theoretical background
Lagrangeowska metoda magnetyzacji dla dwu i trójwymiarowych ruchów płynu lepkiego. Część I - Podstawowe sformułowania
Autorzy:
Styczek, A.
Szumbarski, J.
Powiązania:
https://bibliotekanauki.pl/articles/281483.pdf
Data publikacji:
2002
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
viscous flow
Navier-Stokes equations
magnetization
gauge transform
Opis:
The paper presents the background of an alternative formulation of the Navier-Stokes equation using a variable called the magnetization. Several variants of governing equations, based on different choices of a particular gauge transform, are discussed. The remaining part of the paper is devoted to the formulation of a Lagrangian approach to 2D and 3D viscous flows. First, the carrier of the magnetization (the magneton) is defined and the corresponding induction law is derived. The instantaneous velocity field is constructed as a superposition of contributions from a large set of magnetons and a uniform stream. An essential feature of the method is a one-time-step operator splitting, consisting in the consecutive solution of three sub-problems: generation of the magnetization on solid boudaries, advection-diffusion of the magnetization and sretching.
W artykule przedstawione jest sformułowanie problemu granicznego dla równań Naviera-Stokesa z użyciem tzw. pola magnetyzacji. Sformułowanie nie jest jednoznaczne, lecz wiąże się z przyjętą transformacją cechowania. Rozważane są różne postacie tej transformacji i dokonuje się wyboru odpowiednich wariantów. Pole magnetyzacji przedstawione jest w formie lagrangeowskiej. Wprowadza się cząstki będące źródłami tego pola i określa się związane z ich zbiorem pole prędkości. Cząstki magnetyzacji (zwane magnetonami) poruszają się w indukowanym polu prędkości, wykonują ruch losowy odpowiadający dyfuzji i podlegają przekształceniu w sposób opisany członem źródłowym (tzw. stretching). Warunek brzegowy sformułowany na opływanym ciele jest realizowany przez tworzenie w każdej chwili nowych cząstek ulokowanych w bliskim otoczeniu powierzchni ciała.
Źródło:
Journal of Theoretical and Applied Mechanics; 2002, 40, 2; 339-355
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multiblock parallel computation of an incompressible 3D flow in turbomachines
Autorzy:
Papierski, A.
Rabiega, M.
Powiązania:
https://bibliotekanauki.pl/articles/1954540.pdf
Data publikacji:
1999
Wydawca:
Politechnika Gdańska
Tematy:
numerical simulations
turbomachinery
incompressible flow
3D Navier-Stockes solver
Navier-Stokes solver
parallel computing
Opis:
A finite volume numerical method for the prediction of a fluid flow in complex geometries such as turbomachinery channels has been parallelized using a domain decomposition approach. A mathematical formulation of a 3-D incompressible steady flow has been presented on the basis of the N-S equations in a grid-oriented co-ordinate system with contravariant velocity components. A parallelized pressure-based implicit algorithm with discretization on a staggered grid has been developed. A message exchange system with a boundary exchange, developed by the authors, has been described. Exemplary calculations have been carried out for a laminar flow through a curved duct and for an inviscid flow through a stage of the centrifugal pump. A good agreement has been obtained in both the cases. Despite considerable simplification that has been introduced in the flow through the pump stage, the computations have shown nearly the same pressure rise in the stage as the measurements. Further directions of numerical investigations of a flow through turbomachines, including in particular those devoted to pressure losses related to the rotor-stator interaction, have been mentioned.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 1999, 3, 1; 39-52
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Two-dimensional vertical analysis of dam-break flow
Autorzy:
Zima, P.
Powiązania:
https://bibliotekanauki.pl/articles/1933149.pdf
Data publikacji:
2007
Wydawca:
Politechnika Gdańska
Tematy:
mathematical modeling
Reynolds-averaged Navier-Stokes equations
rapidly varied free surface flow
dam-break flow
Opis:
The paper concerns mathematical modeling of free surface open-channel water flow. Two-dimensional vertical Reynolds-averaged Navier-Stokes equations were used to simulate the flow. They were solved with the SIMPLE algorithm of the finite difference method using the Marker and Cell technique to trace free surface movement. The dam-break flow (water column collapse) problem on a horizontal and frictionless bottom was investigated as a test case. The mechanics of dam-break flow for wet and dry bed conditions was analyzed on the basis of numerical simulations. The obtained results are shown for varying head of water in the downstream channel. The possibility of using the shallow-water equations and the RANS model to simulate rapidly varied flows is discussed.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2007, 11, 4; 315-328
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical investigation of flow in mixed-flow pump with volute
Autorzy:
Sedlar, M.
Powiązania:
https://bibliotekanauki.pl/articles/1967635.pdf
Data publikacji:
2001
Wydawca:
Politechnika Gdańska
Tematy:
CFD
computational fluid dynamics CFD
flow separation
cavitation
Navier-Stokes equation
unsteady phenomena
mixed-flow pump
volute
Opis:
The work considers the modelling of flow in a complete mixed-flow pump with volute, including tip leakage flows, using both quasi-steady and true transient models of rotor/stator interaction. The CFX-TASCflow CFD package from AEA Technology is applied to calculate flows for a wide range of flow rates from about 0.2 to 1.4 Q/sub 0pt/. Fairly detailed flow structures have been predicted based on the flow rates, especially impeller inlet recirculation and separation on the suction side of the blades for suboptimal rates of flow, as well as strong secondary flows and separation in the volute for off-design conditions. The rotor/stator interaction influence on flow phenomena both in the impeller and volute have been investigated with very interesting results, providing good insight into the dynamics of flow close to the volute tongue. Based on the computational results, pump performance curves (Q-H, Q- eta /sub h/ and Q-P, eta /sub h/ being the hydraulic efficiency) have been obtained. The data from this numerical investigation have been used to improve the inlet part of the impeller blades, especially close to the tip. The geometry modifications have resulted in reduced cavitation in the impeller as well as noise at suboptimal rates of flow.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2001, 5, 4; 595-602
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A parallel adaptive code for compressible Navier-Stokes simulations
Autorzy:
Banaś, K.
Powiązania:
https://bibliotekanauki.pl/articles/1954541.pdf
Data publikacji:
1999
Wydawca:
Politechnika Gdańska
Tematy:
numerical simulations
compressible flow
Navier-Stokes solver
finite element method
parallel computing
adaptive meshes
Opis:
The paper presents a finite element code for compressible flow simulations. The code has two important features: adaptivity to increase accuracy of computations by selectively refining a finite element mesh and efficient parallel performance due to a special implementation based on concept of patches of elements. The algorithm for approximating the compressible Navier-Stokes equations is a version of the stabilized finite element method. Three time integration strategies are implemented, explicit, linear implicit and nonlinear implicit, and the GMRES method is used to solve systems of linear equations. For parallel simulations the code uses a special algorithm for mesh partition. The performance of the code is tested for two examples of supersonic flows: one inviscid and one viscous.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 1999, 3, 1; 17-37
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Oil leaks intensity in variable-height gaps
Natężenie przepływu przecieków oleju w szczelinach o zmiennej wysokości
Autorzy:
Zloto, T.
Kowalski, K.
Powiązania:
https://bibliotekanauki.pl/articles/792722.pdf
Data publikacji:
2013
Wydawca:
Komisja Motoryzacji i Energetyki Rolnictwa
Tematy:
variable height gap
hydraulic machine
Navier-Stokes equation
hydraulic oil
oil leakage
flow intensity
Źródło:
Teka Komisji Motoryzacji i Energetyki Rolnictwa; 2013, 13, 2
1641-7739
Pojawia się w:
Teka Komisji Motoryzacji i Energetyki Rolnictwa
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Numerical Study of Combined Natural and Marangoni Convection in a Square Cavity
Autorzy:
Cicek, K.
Baytas, A.
Powiązania:
https://bibliotekanauki.pl/articles/116928.pdf
Data publikacji:
2009
Wydawca:
Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
Tematy:
Numerical Study
Square Cavity
natural convection
Marangoni Convection
Buoyancy-Driven Flow
Thermo Capillary Flow
Navier-Stokes Equations
Rayleigh Number
Opis:
Through the aim of this study, the effects of combined buoyancy-driven flows and thermo capillary flows, which are emerged from temperature differences, on fluid flow and heat transfer numerically investigated with differentially heated side walls in a free surface square cavity. The study has been accomplished with three milestones to achieve the right solutions. For every milestone Navier-Stokes, continuity and energy equations are discretized by using finite volume method and grids with 52 x 52 control volumes. Results are presented Pr=1, Pr=7 and Pr=100. The effect of positive and negative Marangoni number on fluid flow and heat transfer at different Rayleigh number are considered and discussed.
Źródło:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2009, 3, 2; 173-178
2083-6473
2083-6481
Pojawia się w:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Two-dimensional vertical Reynolds-Averaged Navier-Stokes equations versus one-dimensional Saint-Venant model for rapidly varied open channel water flow modelling
Autorzy:
Szydłowski, M.
Zima, P.
Powiązania:
https://bibliotekanauki.pl/articles/241158.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
Tematy:
mathematical modelling
Reynolds-averaged Navier-Stokes equations
Saint-Venant equations
free surface flow
rapidly varied flow
dam-break problem
Opis:
The paper concerns mathematical modelling of free surface open channel water flow. In order to simulate the flow two models are used -- two-dimensional vertical Reynolds-Averaged Navier-Stokes equations and one-dimensional Saint-Venant equations. The former is solved with SIPMLE algorithm of finite difference method using Marker and Cell technique to trace a free surface movement. The latter is solved using the finite volume method. The dam-break (water column collapse) problem on horizontal bottom is investigated as a test case. The calculated results are compared with each other. The numerical simulations are examined against laboratory experiment presented by Koshizuka et al (1995). The possibility of using the described models to simulate rapidly varied flow is discussed.
Źródło:
Archives of Hydro-Engineering and Environmental Mechanics; 2006, 53, 4; 295-309
1231-3726
Pojawia się w:
Archives of Hydro-Engineering and Environmental Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Method of lines for the incompressible Navier-Stokes equations in the stream-function formulation
Autorzy:
Kosma, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1965151.pdf
Data publikacji:
2005
Wydawca:
Politechnika Gdańska
Tematy:
Navier-Stokes equation
stream-function formulation
method of lines
compact schemes
driven cavity
backward-facing step flow
Opis:
The aim of this paper is to simulate the laminar motion of viscous incompressible fluid and the transition between the laminar and the turbulent state in simply connected domains. The developed numerical algorithms are based on the solution of an initial-boundary value problem for the full incompressible Navier-Stokes equations, written in the form of a fourth-order equation for the stream function. The spatial derivatives and the boundary conditions are discretized on uniform grids by means of sixth-order compact schemes together with fourth-order finite-difference formulas, while the continuity of the time variable is preserved. The resulting system of ordinary differential equations has been integrated using the backward-differentiation predictor-corrector method. The efficiency of the numerical algorithms is demonstrated by solving two problems of viscous liquid plane flows in a square driven cavity and a backward-facing step. Calculations for the cavity flow configuration have been obtained for Reynolds numbers ranging from Re=100 to Re=30000 on uniform 50×50 and 100×100 grids. Calculations for the backward-facing step have been made for Re ≤ 3000 with channel lengths, L, within the range 10-30, on 30L×30 uniform grids. The computed stream-function contours and velocity fields have been compared with numerical results reported in the literature.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2005, 9, 1; 17-35
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Implementation of turbulence damping in the OpenFOAM multiphase flow solver interFoam
Autorzy:
Polansky, Jiri
Schmelter, Sonja
Powiązania:
https://bibliotekanauki.pl/articles/2091357.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
multiphase flow
stratified flow
turbulence damping
computational fluid dynamics
OpenFOAM
Reynolds-averaged Navier–Stokes
Detached Eddy Simulation
Delayed Detached Eddy Simulation
Opis:
In the presented work Egorov’s approach (adding a source term to the ω-equation in the k-ω model, which mimics the damping of turbulence close to a solid wall) was implemented in on the subclass of shear stress transport models. Hence, turbulence damping is available for all shear stress transport type models, including hybrid models that are based on the ω-equation. It is shown that turbulence damping improves the prediction of the axial velocity profile not only for Reynolds-averaged Navier–Stokes simulation but also for detached eddy simulation and delayed detached eddy simulation models. Furthermore, it leads to a more realistic estimation of the pressure drop and, hence, to a more correct prediction of the liquid level. In this paper, simulation results for four different turbulence models are presented and validated by comparison with experimental data. Furthermore, the influence of the magnitude of the damping factor on the pressure drop in the channel is investigated for a variety of different gas-to-liquid flow rate ratios. These investigations show that higher gas-to-liquid flow rate ratios require higher damping factors to correctly predict the pressure drop. In the end, advice is formulated on how an appropriate damping factor can be determined for a specific test case.
Źródło:
Archives of Thermodynamics; 2022, 43, 1; 21--43
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of CFD for analysis of the ship and propeller flow
Autorzy:
Bugalski, T. J.
Szantyr, J.
Powiązania:
https://bibliotekanauki.pl/articles/1953974.pdf
Data publikacji:
1998
Wydawca:
Politechnika Gdańska
Tematy:
computational fluid dynamics CFD
CFD
propeller flow
ships
Navier-Stokes equation
free surface
propeller operation
PANSHIP computer system
Opis:
The paper describes the computer system PANSHIP for analysis of flow around the ship hull moving with constant velocity in calm water, including the effects of free surface and propeller operation. This system calculates the potential flow using the discrete distribution of Rankine sources on the hull. Viscous flow is computed using the integral method in the bow section and Reynolds averaged Navier Stokes equation (RANS) in the stern section of the ship hull. Results of this analysis may be directly used in ship hull design and they may also serve as input for calculation of the unsteady flow phenomena accompanying propeller operation in the non-uniform velocity field generated by the hull. PANSHIP has been verified experimentally and it forms a useful tool available for ship designers and for marine hydrodynamicists.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 1998, 2, 2; 349-356
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
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
Artykuł
Tytuł:
Novel method of physical modes generation for reduced order flow control-oriented models
Autorzy:
Morzyński, M.
Nowak, M.
Stankiewicz, W.
Powiązania:
https://bibliotekanauki.pl/articles/127922.pdf
Data publikacji:
2014
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Tematy:
Navier-Stokes equation
eigenmodes
Reduced Order Modelling
flow control
równanie Naviera-Stokesa
postać drgań własnych
modelowanie zredukowanego rzędu
kontrola przepływu
Opis:
Physical flow modes are of particular interest for Reduced Order Flow Control-Oriented Models. Computation of physical modes as the eigensolution of linearized Navier-Stokes equations is a cumbersome and difficult task, especially for large, 3D problems. Instead we propose the solution of Navier-Stokes equation in the frequency domain and investigation of the system response to local or global perturbation. The flow variables are perturbed around steady basic state and the system response is used to construct mode basis suitable for ROMs.
Źródło:
Vibrations in Physical Systems; 2014, 26; 189-194
0860-6897
Pojawia się w:
Vibrations in Physical Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 22

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