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Wyświetlanie 1-45 z 45
Tytuł:
Shape optimization for stationary Navier-Stokes equations
Autorzy:
Halanay, A.
Tiba, D.
Powiązania:
https://bibliotekanauki.pl/articles/970751.pdf
Data publikacji:
2009
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
optimal design
optimal control method
fluid mechanics
penalization
gradient method
Opis:
This work discusses geometric optimization problems governed by stationary Navier-Stokes equations. Optimal domains are proved to exist under the assumption that the family of admissible domains is bounded and satisfies the Lipschitz condition with a uniform constant, and in the absence of the uniqueness property for the state system. Through the parametrization of the admissible shapes by continuous functions defined on a larger universal domain, the optimization parameter becomes a control, i.e. an element of that family of continuous functions. The approximating extension technique via the penalization of the Navier-Stokes equation enables the approximation of the associated shape optimization problem by an optimal control problem. Results on existence and uniqueness are proved for the approximating problem and a gradient-type algorithm is indicated.
Źródło:
Control and Cybernetics; 2009, 38, 4B; 1359-1374
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Conditions for the solvability of a nonlinear boundary value problem of the flow of a viscous fluid
Autorzy:
Studziński, Jan
Powiązania:
https://bibliotekanauki.pl/articles/747617.pdf
Data publikacji:
1985
Wydawca:
Polskie Towarzystwo Matematyczne
Tematy:
Navier-Stokes equations
Opis:
.
The author presents a discussion of existence, uniqueness and convergence of finite difference approximations for Navier-Stokes equations with convection in a two-dimensional rectangle with sufficiently small data.
Źródło:
Mathematica Applicanda; 1985, 12, 24
1730-2668
2299-4009
Pojawia się w:
Mathematica Applicanda
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Regularity and stability of optimal controls of nonstationary Navier-Stokes equations
Autorzy:
Wachsmuth, D.
Powiązania:
https://bibliotekanauki.pl/articles/970093.pdf
Data publikacji:
2005
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
sterowanie optymalne
równanie Naviera-Stokesa
stabilność Lipschitza
optimal control
Navier-Stokes equations
control constraints
Lipschitz stability
Opis:
The regularity and stability of optimal controls of nonstationary Navier-Stokes equations are investigated. Under suitable assumptions every control satisfying first-order necessary conditions is shown to be a continuous function in both space and time. Moreover, the behaviour of a locally optimal control under certain perturbations of the cost functional and the state equation is investigated. Lipschitz stability is proven provided a second-order sufficient optimality condition holds.
Źródło:
Control and Cybernetics; 2005, 34, 2; 387-409
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Energy Method for Elastic Problems With Non-Homogeneous Boundary Conditions
Autorzy:
Quintanilla, R.
Powiązania:
https://bibliotekanauki.pl/articles/907887.pdf
Data publikacji:
2002
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
matematyka
weighted energy method
decay estimates
Navier equations
non-homogeneous boundary conditions
Opis:
In this paper we propose the weighted energy method as a way to study estimates of solutions of boundary-value problems with non-homogeneous boundary conditions in elasticity. First, we use this method to study spatial decay estimates in two-dimensional elasticity when we consider non-homogeneous boundary conditions on the boundary. Some comments in the case of harmonic vibrations are considered as well. We also extend the arguments to a class of three-dimensional problems in a cylinder. A section is devoted to the study of an ill-posed problem. Some remarks are presented in the last section of the paper.In this paper we propose the weighted energy method as a way to study estimates of solutions of boundary-value problems with non-homogeneous boundary conditions in elasticity. First, we use this method to study spatial decay estimates in two-dimensional elasticity when we consider non-homogeneous boundary conditions on the boundary. Some comments in the case of harmonic vibrations are considered as well. We also extend the arguments to a class of three-dimensional problems in a cylinder. A section is devoted to the study of an ill-posed problem. Some remarks are presented in the last section of the paper.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2002, 12, 1; 91-100
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Shape derivatives for general objective functions and the incompressible Navier-Stokes equations
Autorzy:
Schmidt, S.
Schulz, V.
Powiązania:
https://bibliotekanauki.pl/articles/969869.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
shape optimization
shape derivative
Navier-Stokes
adjoint calculus
Opis:
The aim of this paper is to present the shape derivative for a wide array of objective functions using the incompressible Navier-Stokes equations as a state constraint. Most real world applications of computational fluid dynamics are shape optimization problems in nature, yet special shape optimization techniques are seldom used outside the field of elliptic partial differential equations and linear elasticity. This article tries to be self contained, also presenting many useful results from the literature. We conclude with a comparison of different objective functions for the shape optimization of an obstacle in a channel, which can be done quite conveniently when one knows the general form of the shape gradient.
Źródło:
Control and Cybernetics; 2010, 39, 3; 677-713
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Shape optimization in problems governed by generalised Navier-Stokes equations: existence analysis
Autorzy:
Haslinger, J.
Malek, J.
Stebel, J.
Powiązania:
https://bibliotekanauki.pl/articles/970130.pdf
Data publikacji:
2005
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
optimal shape design
paper machine headbox
incompressible non-Newtonian fluid
algebraic turbulence model
Opis:
We study a shape optimization problem for a paper machine headbox which distributes a mixture of water and wood fibers in the paper manufacturing process. The aim is to find a shape which a priori ensures the given velocity profile on the outlet part. The mathematical formulation leads to an optimal control problem in which the control variable is the shape of the domain representing the header, the state problem is represented by the generalised Navier-Stokes system with nontrivial boundary conditions. The objective of this paper is to prove the existence of an optimal shape.
Źródło:
Control and Cybernetics; 2005, 34, 1; 283-303
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Lipschitz stability of optimal controls for the steady-state Navier-Stokes equations
Autorzy:
Roubicek, T.
Troltzsch, F.
Powiązania:
https://bibliotekanauki.pl/articles/970527.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
sterowanie strumieniem danych
stabilność Lipschitza
incompressible viscous fluids
flow control
first and second order optimality conditions
Lipschitz stability
Opis:
An optimal control problem with quadratic cost functional for the steady-state Navier-Stokes equations with no-slip boundary condition is considered. Lipschitz stability of locally optimal controls with respect to certain perturbations of both the cost functional and the equation is proved provided a second-order sufficient optimality condition holds. For a sufficiently small Reynolds number, even global Lipschitz stability of the unique optimal control is shown.
Źródło:
Control and Cybernetics; 2003, 32, 3; 683-705
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some application of the implicit function theorem to the stationary Navier-Stokes equations
Autorzy:
Holly, Konstanty
Powiązania:
https://bibliotekanauki.pl/articles/1313290.pdf
Data publikacji:
1991
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Opis:
We prove that - in the case of typical external forces - the set of stationary solutions of the Navier-Stokes equations is the limit of the (full) sequence of sets of solutions of the appropriate Galerkin equations, in the sense of the Hausdorff metric (for every inner approximation of the space of velocities). Then the uniqueness of the N-S equations is equivalent to the uniqueness of almost every of these Galerkin equations.
Źródło:
Annales Polonici Mathematici; 1991, 54, 2; 93-109
0066-2216
Pojawia się w:
Annales Polonici Mathematici
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Global existence for a one-dimensional model in gas dynamics
Autorzy:
Njamkepo, Serge
Powiązania:
https://bibliotekanauki.pl/articles/1339279.pdf
Data publikacji:
1997
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
capillarity
Navier-Stokes equations
gas dynamics
Opis:
We prove the existence of a global solution for a one-dimensio- nal Navier-Stokes system for a gas with internal capillarity.
Źródło:
Applicationes Mathematicae; 1996-1997, 24, 2; 203-221
1233-7234
Pojawia się w:
Applicationes Mathematicae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Liquid Metal Movements on the Casting Creation
Autorzy:
Sowa, Leszek
Skrzypczak, Tomasz
Kwiatoń, Paweł
Powiązania:
https://bibliotekanauki.pl/articles/2049715.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
numerical simulations
solidification
Navier-Stokes equations
Opis:
Knowledge about complex physical phenomena used in the casting process simulation requires continuous complementary research and improvement in mathematical modeling. The basic mathematical model taking into account only thermal phenomena often becomes insufficient to analyze the process of metal solidification, therefore more complex models are formulated, which include coupled heat-flow phenomena, mechanical or shrinkage phenomena. However, such models significantly complicate and lengthen numerical simulations; therefore the work is limited only to the analysis of coupled thermal and flow phenomena. The mathematical description consists then of a system of Navier-Stokes differential equations, flow continuity and energy. The finite element method was used to numerically modeling this problem. In computer simulations, the impact of liquid metal movements on the alloy solidification process in the casting-riser system was assessed, which was the purpose of this work, and the locations of possible shrinkage defects were pointed out, trying to ensure the right supply conditions for the casting to be free from these defects.
Źródło:
Archives of Metallurgy and Materials; 2021, 66, 2; 489-495
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the numerical solution of one inverse problem for a linearized two-dimensional system of Navier-Stokes equations
Autorzy:
Jenaliyev, Muvasharkhan
Ramazanov, Murat
Yergaliyev, Madi
Powiązania:
https://bibliotekanauki.pl/articles/2216154.pdf
Data publikacji:
2022
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Navier-Stokes equations
inverse problem
numerical solution
Opis:
The paper studies the numerical solution of the inverse problem for a linearized two-dimensional system of Navier-Stokes equations in a circular cylinder with a final overdetermination condition. For a biharmonic operator in a circle, a generalized spectral problem has been posed. For the latter, a system of eigenfunctions and eigenvalues is constructed, which is used in the work for the numerical solution of the inverse problem in a circular cylinder with specific numerical data. Graphs illustrating the results of calculations are presented.
Źródło:
Opuscula Mathematica; 2022, 42, 5; 709-725
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
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:
On shape sensitivity analysis of the cost functional without shape sensitivity of the state variable
Autorzy:
Kasumba, H.
Kunisch, K.
Powiązania:
https://bibliotekanauki.pl/articles/206115.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
shape derivative
Navier-Stokes equations
cost functional
Opis:
A general framework for calculating shape derivatives for domain optimization problems with partial differential equations as constraints is presented. The first order approximation of the cost with respect to the geometry perturbation is arranged in an efficient manner that allows the computation of the shape derivative of the cost without the necessity to involve the shape derivative of the state variable. In doing so, the state variable is only required to be Lipschitz continuous with respect to geometry perturbations. Application to shape optimization with the Navier-Stokes equations as PDE constraint is given.
Źródło:
Control and Cybernetics; 2011, 40, 4; 989-1017
0324-8569
Pojawia się w:
Control and Cybernetics
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:
Difference melt model
Autorzy:
Kazhikenova, Saule Sh.
Shaltakov, Sagyndyk N.
Nussupbekov, Bekbolat R.
Powiązania:
https://bibliotekanauki.pl/articles/1845514.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Navier-Stokes equations
hydrodynamic
approximations
mathematical models
melt
Opis:
The basic objective of the research is to construct a difference model of the melt motion. The existence of a solution to the problem is proven in the paper. It is also proven the convergence of the difference problem solution to the original problem solution of the melt motion. The Rothe method is implemented to study the Navier-Stokes equations, which provides the study of the boundary value problems correctness for a viscous incompressible flow both numerically and analytically.
Źródło:
Archives of Control Sciences; 2021, 31, 3; 607-627
1230-2384
Pojawia się w:
Archives of Control Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Difference melt model
Autorzy:
Kazhikenova, Saule Sh.
Shaltakov, Sagyndyk N.
Nussupbekov, Bekbolat R.
Powiązania:
https://bibliotekanauki.pl/articles/1845525.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Navier-Stokes equations
hydrodynamic
approximations
mathematical models
melt
Opis:
The basic objective of the research is to construct a difference model of the melt motion. The existence of a solution to the problem is proven in the paper. It is also proven the convergence of the difference problem solution to the original problem solution of the melt motion. The Rothe method is implemented to study the Navier-Stokes equations, which provides the study of the boundary value problems correctness for a viscous incompressible flow both numerically and analytically.
Źródło:
Archives of Control Sciences; 2021, 31, 3; 607-627
1230-2384
Pojawia się w:
Archives of Control Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of a near wall model to Navier-Stokes equations with nonlinear time-relaxation model
Autorzy:
İhan, Özgül
Powiązania:
https://bibliotekanauki.pl/articles/2175530.pdf
Data publikacji:
2022
Wydawca:
Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
Tematy:
boundary layers
laminar
near wall models
NWM
Navier-Stokes equation with nonlinear time-relaxation model
NSE-NTR
warstwy graniczne
równanie Naviera-Stokesa z nieliniowym modelem relaksacji w czasie
Opis:
It is difficult and essential to determine appropriate boundary conditions for the flow averages because they depend on the behavior of the unknown flow near the wall. Large-eddy simulation (LES) is one of the promising approaches. LES estimates local spatial averages ū of the velocity u of the fluid. The main problem is modeling near-wall turbulence in complex geometries. Inspired by the works of Navier and Maxwell, the boundary conditions are developed on the wall. In this study, the appropriate friction coefficient for 2-D laminar flows is computed, and existing boundary layer theories are used to improve numerical boundary conditions for flow averages. The slip with friction and penetration with resistance boundary conditions are considered. Numerical tests on two-dimensional channel flow across a step using this boundary condition on the top and bottom wall and the step are performed.
Źródło:
Journal of Applied Mathematics and Computational Mechanics; 2022, 21, 2; 39--50
2299-9965
Pojawia się w:
Journal of Applied Mathematics and Computational 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:
The unique solvability of stationary and non-stationary incompressible melt models in the case of their linearization
Autorzy:
Kazhikenova, Saule Sh.
Powiązania:
https://bibliotekanauki.pl/articles/1409389.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Navier-Stockes equations
hydrodynamic
approximations
mathematical models
incompressible melt
Opis:
The article presents ε-approximation of hydrodynamics equations’ stationary model along with the proof of a theorem about existence of a hydrodynamics equations’ strongly generalized solution. It was proved by a theorem on the existence of uniqueness of the hydrodynamics equations’ temperature model’s solution, taking into account energy dissipation. There was implemented the Galerkin method to study the Navier-Stokes equations, which provides the study of the boundary value problems correctness for an incompressible viscous flow both numerically and analytically. Approximations of stationary and non-stationary models of the hydrodynamics equations were constructed by a system of Cauchy-Kovalevsky equations with a small parameter ε. There was developed an algorithm for numerical modelling of the Navier-Stokes equations by the finite difference method.
Źródło:
Archives of Control Sciences; 2021, 31, 2; 307-332
1230-2384
Pojawia się w:
Archives of Control Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Computations of an unsteady viscous flow in a three dimensional system of ducts. Part I: Formulation of the mathematical problem and numerical method
Autorzy:
Szumbarski, J.
Olszewski, P.
Styczek, A.
Rokicki, J.
Powiązania:
https://bibliotekanauki.pl/articles/280661.pdf
Data publikacji:
2004
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
Navier-Stokes equations
defective boundary conditions
spectral element method
Opis:
Numerical modeling of an unsteady flow of a viscous incompressible fluid inside a branched pipe system is considered. The mathematical formulation is given with special emphasis on inlet/outlet conditions. The equivalent weak form of the initial-boundary value problem is presented. The numerical method based on solutions to particular Stokes problems is proposed and described in some details. Finally, some general remarks about the implementation issues within the framework of the spectral element discretization are made.
W pracy rozważono problem numerycznego wyznaczania nieustalonego przepływu cieczy lepkiej w układzie trójwymiarowych przewodów. Podano sformułowanie wariacyjne zagadnienia uwzględniające uogólnione warunki brzegowe na wlotach/wylotach do obszaru ruchu. Opisano metodę obliczeniową, opartą na zastosowaniu wskaźników Lagrange'a i superpozycji szczególnych problemów Stokesa w każdym kroku czasowym.
Źródło:
Journal of Theoretical and Applied Mechanics; 2004, 42, 1; 21-39
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Shape sensitivity analysis of time-dependent flows of incompressible non-Newtonian fluids
Autorzy:
Sokołowski, J.
Stebel, J.
Powiązania:
https://bibliotekanauki.pl/articles/206105.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
shape optimization
shape gradient
incompressible viscous fluid
Navier-Stokes equations
Opis:
We study the shape differentiability of a cost function for the flow of an incompressible viscous fluid of power-law type. The fluid is confined to a bounded planar domain surrounding an obstacle. For smooth perturbations of the shape of the obstacle we express the shape gradient of the cost function which can be subsequently used to improve the initial design.
Źródło:
Control and Cybernetics; 2011, 40, 4; 1077-1097
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical simulation of compressible flow through cascade of profiles
Autorzy:
Dolejší, V.
Powiązania:
https://bibliotekanauki.pl/articles/1986687.pdf
Data publikacji:
2002
Wydawca:
Politechnika Gdańska
Tematy:
compressible Navier-Stockes equations
combined finite volume
finite element method
anisotropic mesh adaptation
Opis:
We deal with the numerical simulation of flow through a steam turbine. The system of the compressible Navier-Stokes equations accompanied by the state equation of perfect gas are numerically solved. We propose a new approach for the numerical solution of the Navier-Stokes equations, where the inviscid part is discretized by the finite volume method and the viscous part by the finite element method. To capture precisely the position of shock waves, the suitable mesh refinement method has to be applied. Therefore the anisotropic mesh adaptation technique equipped with some suitable modification for viscous compressible flow is used. The suitable application of the mentioned numerical adaptive method allows us to obtain sufficiently precise results without much requirement on CPU-time and computer memory.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2002, 6, 1; 177-186
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Computations of an unsteady viscous flow in a three-dimensional system of ducts. Part II: Implementation of the spectral element method and sample results
Wyznaczanie nieustalonych przepływów cieczy lepkiej w trójwymiarowym układzie przewodów. Część II: Implementacja metody spektralnych elementów skończonych i przykładowe wyniki
Autorzy:
Szumbarski, J.
Olszewski, P.
Wawruch, K.
Małota, Z.
Powiązania:
https://bibliotekanauki.pl/articles/281860.pdf
Data publikacji:
2004
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
Navier-Stokes equations
spectral element methods
pressure preconditioners
fast diagonalization
parallel computations
Opis:
The second part the paper focuses on implementation issues of the spectral element technique and presents sample results of numerical simulations. Particular algorithms like preconditioning of the presser solver, fast diagonalization method and the projection method for solving sequences of large linear systems are described in some details. The computational results, obtained for both test domains and geometries of medical origin, are presented. The comparison with the results of computations with the FIDAP package is provided. The difficulties and limitations of the spectral method and current implementation are discussed. Attempts of the parallelization of the spectral code and the obtained efficiency are briefly described.
Druga część pracy omawia zagadnienia związane z implementacją metody spektralnych elementów skończonych oraz prezentuje wybrane wyniki obliczeń. Przedstawiono również wybrane algorytmy: skalowanie (ang. preconditioning) procesu iteracyjnego dla ciśnienia, metodę FDM oraz metodę efektywnego rozwiązywania sekwencji układów liniowych dużych rozmiarów z ustaloną macierzą. Omówiono wyniki obliczeń testowych. Przedyskutowano trudności i ograniczenia aktualnej implementacji oraz zaprezentowano wstępne efekty paralelizacji solwera spektralnego.
Źródło:
Journal of Theoretical and Applied Mechanics; 2004, 42, 4; 869-903
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
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:
Shape Optimization of Labyrinth Seals
Autorzy:
Aboulaich, R.
Azelmat, K.
Baranger, J.
Souissi, A.
Powiązania:
https://bibliotekanauki.pl/articles/911193.pdf
Data publikacji:
2000
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
optymalizacja
metoda elementów skończonych
shape optimization
hydraulic turbine
Navier-Stokes equations
finite element method
Opis:
In this work, we determine the optimal shape of a labyrinth seal in a hydraulic Francis turbine. The numerical approximation of the optimal shape is obtained using shape optimization techniques. The flow is governed by Navier-Stokes equations. We first prove the existence of an optimal domain, and later we present the computation of the shape gradient which allows us to approximate numerically the optimal domain.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2000, 10, 2; 381-404
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
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:
On local existence of solutions of the free boundary problem for an incompressible viscous self-gravitating fluid motion
Autorzy:
Mucha, Piotr
Zajączkowski, Wojciech
Powiązania:
https://bibliotekanauki.pl/articles/1208168.pdf
Data publikacji:
2000
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
anisotropic Sobolev space
Navier-Stokes equations
local existence
sharp regularity
incompressible viscous barotropic self-gravitating fluid
Opis:
The local-in-time existence of solutions of the free boundary problem for an incompressible viscous self-gravitating fluid motion is proved. We show the existence of solutions with lowest possible regularity for this problem such that $u\in W^{2,1}_r(\widetilde{{\mitΩ}}^T)$ with r>3. The existence is proved by the method of successive approximations where the solvability of the Cauchy-Neumann problem for the Stokes system is applied. We have to underline that in the $L_p$-approach the Lagrangian coordinates must be used. We are looking for solutions with lowest possible regularity because this simplifies the proof and decreases the number of compatibility conditions.
Źródło:
Applicationes Mathematicae; 2000, 27, 3; 319-333
1233-7234
Pojawia się w:
Applicationes Mathematicae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamic programming approach to structural optimization problem - numerical algorithm
Autorzy:
Fulmański, P.
Nowakowski, A.
Pustelnik, J.
Powiązania:
https://bibliotekanauki.pl/articles/255706.pdf
Data publikacji:
2014
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
elliptic equations
optimal shape control
structural optimization
stationary Navier-Stokes equations
dynamic programming
sufficient optimality condition
numerical approximation
Opis:
In this paper a new shape optimization algorithm is presented. As a model application we consider state problems related to fluid mechanics, namely the Navier-Stokes equations for viscous incompressible fluids. The general approach to the problem is described. Next, transformations to classical optimal control problems are presented. Then, the dynamic programming approach is used and sufficient conditions for the shape optimization problem are given. A new numerical method to find the approximate value function is developed.
Źródło:
Opuscula Mathematica; 2014, 34, 4; 699-724
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On free convection heat transfer from vertical plate - proposition of a new model
Autorzy:
Leble, S.
Lewandowski, W. M.
Powiązania:
https://bibliotekanauki.pl/articles/1938587.pdf
Data publikacji:
2016
Wydawca:
Politechnika Gdańska
Tematy:
Navier-Stokes equations
Fourier-Kirchhoff equation
free convective heat transfer
analytical solution
sothermal surface
boundary layer
vertical plate
Opis:
The free convection heat transfer from an isothermal vertical plate in open space is investigated theoretically. In contrast to conventional approaches we use neither boundary layer nor self-similarity concepts. We base on expansion of the fields of velocity and temperature in a Taylor Series in x coordinate with coefficients being functions of the vertical coordinate (y). In the minimal version of the theory we restrict ourselves by cubic approximation for both functions. The Navier-Stokes and Fourier-Kirchhoff equations that describe the phenomenon give links between coefficient functions of y that after exclusion leads to the ordinary differential equation of forth order (of the Mittag-Leffleur type). Such construction implies four boundary conditions for a solution of this equation while the links between the coefficients need two extra conditions. All the conditions are chosen on the basis of the experience usual for free convection. The choice allows us to express all the theory parameters as functions of the Rayleigh number and the temperature difference. To support the conformity of the theory we derive the Nusselt-Rayleigh numbers relation that has the traditional form. The solution in the form of velocity and temperature profiles is evaluated and illustrated for air by examples of plots of data.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2016, 20, 2; 249-265
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mathematical modeling of fluid flow in the doubly connected area
Matematyczne modelowanie przepływu cieczy w dwuwymiarowym obszarze
Autorzy:
Kopylov, S.
Szafran, K.
Powiązania:
https://bibliotekanauki.pl/articles/213070.pdf
Data publikacji:
2016
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Lotnictwa
Tematy:
non-Newtonian fluid
doubly connected region
Navier-Stokes equations
płyn nieniutonowski
przestrzeń dwuwymiarowa
prędkość lokalna
równanie Naviera-Stokesa
Opis:
The article presents the study of the flow of non-Newtonian liquid on the hydrodynamic initial section in doubly connected region. A method which allows solving this problem is to use the principle of conservation of momentum for a moving fluid. The study used the equation Navier- Stokesa for in viscid fluid moving in a two dimensional space. For the solution of the Navier-Stokes equations it is necessary to know the function of cross linking for the velocity distribution in hydrodynamic initial section in doubly connected region. This function was obtained by integrating the Navier-Stokes equations and after substitution in the equation for the distribution of local velocities allows calculating the local velocity in the liquid flow on the hydrodynamic initial section in doubly connected region. In addition to the analysis of the function of cross linking was discussed.
W artykule przedstawiono analizę przepływu cieczy nienewtonowskiej na styku początkowym podwójnie połączonego odcinka hydraulicznego. Sposób, który pozwala na rozwiązanie tego problemu to jest zastosowanie zasady zachowania pędu do poruszającego się płynu. W badaniu analitycznym zastosowano równanie Naviera-Stokesa dla lepkiego płynu poruszającego się w przestrzeni dwuwymiarowej. Do układu równań Naviera-Stokesa należy wprowadzić funkcję sieciowania dla rozkładu prędkości na początku przepływu hydrodynamicznego w dwuwymiarowym obszarze. Funkcję otrzymano przez całkowanie równań Naviera-Stokesa. Po podstawieniu do równań dla rozkładu lokalnych prędkości umożliwiło to obliczenie lokalnej prędkości w cieczy w dwuwymiarowym przepływie hydrodynamicznym.
Źródło:
Prace Instytutu Lotnictwa; 2016, 4 (245); 218-226
0509-6669
2300-5408
Pojawia się w:
Prace Instytutu Lotnictwa
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:
Mathematical challenges in shape optimization
Autorzy:
Henrot, A.
Sokołowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/970146.pdf
Data publikacji:
2005
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
optymalizacja kształtu
optymalizacja topologiczna
zagadnienie znajdowania wartości własnych
równanie Naviera-Stokesa
Navier-Stokes equations
shape optimization
topology optimization
eingenvalue problem
Opis:
Activities of the CNRS programme GDR shape optimization are described. Recent developments in shape optimization for eigenvalues and drag minimization are presented.
Źródło:
Control and Cybernetics; 2005, 34, 1; 37-57
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Symulacja zjawiska pierścienia wirowego wokół wirnika śmigłowca w oparciu o rozwiązanie równań Naviera-Stokesa z uproszczonym modelem wirnika w postaci powierzchni skoku ciśnienia
Vortex ring state around helicopter rotor simulation using Navier-Stokes equations and actuator disc model
Autorzy:
Stalewski, W.
Dziubiński, A.
Powiązania:
https://bibliotekanauki.pl/articles/212751.pdf
Data publikacji:
2006
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Lotnictwa
Tematy:
symulacja zjawiska pierścienia wirowego
wirnik śmigłowca
równania Naviera-Stokesa
uproszczony model wirnika
vortex ring state
helicopter rotor simulation
Navier-Stokes equations
Opis:
W pracy omówiono zjawisko pierścienia wirowego oraz przedstawiono metodę komputerowej symulacji tego zjawiska. Metoda bazuje na rozwiązaniu równań Naviera-Stokesa opisujących niestacjonarny opływ śmigłowca wykonującego manewry. Zastosowano uproszczony model wirnika śmigłowca bazujący na powierzchni skoku ciśnienia. Symulacje przeprowadzono przy wykorzystaniu komercyjnego programu FLUENT rozwiązującego równania Naviera-Stokesa metodą objętości skończonych. Przedstawiono wyniki symulacji typowego lotu śmigłowca wprowadzającego go w stan pierścienia wirowego oraz manewrów umożliwiających wyjście z tego stanu.
This work contains the simulations results of Vortex Ring State appearance and evolution around main rotor of a helicopter. These calculations were based on solution of Navier-Stokes equations using the Fluent code. During this simulation An Actuator Disc model of fan has been used. This model assumes that a fan is a pressure jump generating surface. Two mashes has been used during this simulation: three dimensional and axisymmetrical two-dimensional. The most of the cases has been calculated using steady flow solutions, but unsteady model also has been applied. Main goal of this work was a calibration of model, in terms of simplifications influence on results, and also in comparison with experimental results. Two different conditions of flight has been considered: hover and vertical descent with various velocities along axis of rotor. The results has been analyzed to determinate Vortex Ring State conditions and confirmed, that Actuator Disc model can be used to qualitative analisys of VRS phenomena. It is assumed, that after a proper calibration this model can be used in further flight safety methods of VRS elimination research.
Źródło:
Prace Instytutu Lotnictwa; 2006, 1-2 (184-185); 65-71
0509-6669
2300-5408
Pojawia się w:
Prace Instytutu Lotnictwa
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical Simulation of Nonlinear Water Wave Problems
Autorzy:
Lo, D. C.
Hu, Jia-Shen
Lin, I-Fu
Powiązania:
https://bibliotekanauki.pl/articles/116613.pdf
Data publikacji:
2008
Wydawca:
Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
Tematy:
Weather Navigation
Numerical Simulation
Oceanography
Nonlinear Water Wave Problem
Navier-Stokes Equations
Solitary Waves
Free-Surface Flow Problem
Streamfunction Vorticity Formulation
Opis:
The main purpose of present paper aims at the establishment of a numerical model for solving the nonlinear water wave problems. The model is based on the Navier-Stokes equations with the consideration of a free-surface through the streamfunction-vorticity formulation. The main advantage of the streamfunction-vorticity formulation is that pressure field can be eliminated from the Navier-Stokes equations. To demonstrate the model feasibility, the present studies are first concentrated on problems including the collision of two solitary waves with different amplitudes, and the overtaking collision of two solitary waves. Then, the model is also applied to a solitary wave passes over the submerged obstacle in a viscous fluid. Finally, the application of present study is also to simulate the generation of solitary waves by underwater moving object. All examples give very promising results, those applications reveal that present formulation is a very powerful approach to simulate the fully nonlinear water wave problems.
Źródło:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2008, 2, 2; 137-142
2083-6473
2083-6481
Pojawia się w:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Efficient simulations of large-scale convective heat transfer problems
Autorzy:
Goik, Damian
Banaś, Krzysztof
Bielański, Jan
Chłoń, Kazimierz
Powiązania:
https://bibliotekanauki.pl/articles/2097965.pdf
Data publikacji:
2021
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
convective heat transfer
finite element method
sparse linear equations
algebraic multigrid
Navier–Stokes equations
GMRES
block preconditioning
SUPG stabilization
MPI
PETSc
scalability
Opis:
We describe an approach for efficient solution of large-scale convective heat transfer problems that are formulated as coupled unsteady heat conduction and incompressible fluid-flow equations. The original problem is discretized over time using classical implicit methods, while stabilized finite elements are used for space discretization. The algorithm employed for the discretization of the fluid-flow problem uses Picard’s iterations to solve the arising nonlinear equations. Both problems (the heat transfer and Navier–Stokes equations) give rise to large sparse systems of linear equations. The systems are solved by using an iterative GMRES solver with suitable preconditioning. For the incompressible flow equations, we employ a special preconditioner that is based on an algebraic multigrid (AMG) technique. This paper presents algorithmic and implementation details of the solution procedure, which is suitably tuned – especially for ill-conditioned systems that arise from discretizations of incompressible Navier–Stokes equations. We describe a parallel implementation of the solver using MPI and elements from the PETSC library. The scalability of the solver is favorably compared with other methods, such as direct solvers and the standard GMRES method with ILU preconditioning.
Źródło:
Computer Science; 2021, 22 (4); 517--538
1508-2806
2300-7036
Pojawia się w:
Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mathematical modelling of the process of pipeline deformation through which gas-liquid mixtures with aggressive components are transported
Autorzy:
Oliynyk, A. P.
Feshanych, L. I.
Grygorchuk, G. V.
Powiązania:
https://bibliotekanauki.pl/articles/2172155.pdf
Data publikacji:
2022
Wydawca:
Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
Tematy:
tense state
pipeline
viscous fluid flow
dynamic viscosity
Navier-Stokes equations
gas mixture
rurociąg
lepkość dynamiczna
równania Naviera-Stokesa
mieszanka gazowa
Opis:
Purpose Mathematical modelling of the process of deformation of pipeline, transporting gas-liquid mixtures with aggressive components and a comparative analysis of the value of the specified velocity depending on the dynamic viscosity of the multicomponent gas mixture is conducted. Design/methodology/approach A mathematical model of the process of leakage of the transported product due to the loss of tightness of the pipe based on the system of Navier-Stokes equations with boundary conditions with considering the geometry of the leakage zones and the value of the leakage rate is implemented. Findings Models of the process of deformation of the pipeline due to displacements of a certain set of surface points by specifying different types of functions, describing the geometry of deformed sections are constructed. The method of calculating the tensely deformed state based on the data on the movement of surface points by comparing different ways of setting functions, taking into account the actual configuration of sections and axes is improved. The change of flow characteristics in the pipeline when changing the structure of the mix, transported by studying of influence of change of dynamic viscosity is investigated; The method of calculating the rate of leakage of the mixture in case of loss of tightness due to the occurrence of critical stresses in the pipe material is improved. Research limitations/implications Building a model of the deformation process, information about the nature, duration of forces and loads affecting the pipeline is not used. The law of the pipeline movement was constructed having taken into account the deformation of the sections in three directions. The necessity to take wind loads into account, estimating the real tensely deformed state was displayed. Practical implications Using the method of calculating the tensely deformed state based on the data on the movement of surface points by comparing different ways of setting functions, taking into account the actual configuration of sections and axes. Originality/value According to the computational algorithms created on the basis of the specified models, the calculations of the tense state of the pipelines and the flow rate of the mixture depending on its composition were performed. An analysis of the results of calculations - tense intensity and flow rate depending on the dynamic viscosity of the mixture is performed. The influence on the flow parameters - the flow rate of the mixture and the force of hydraulic resistance - changes in the dynamic viscosity of the mixture is analyzed.
Źródło:
Journal of Achievements in Materials and Manufacturing Engineering; 2022, 111, 2; 57--63
1734-8412
Pojawia się w:
Journal of Achievements in Materials and Manufacturing Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
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
Artykuł
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
Artykuł
Tytuł:
An influence matrix technique for multi-domain solution of the Navier-Stokes equations in a vorticity-streamfunction formulation
Zastosowanie metody macierzy wpływu w połączeniu z metodą dekompozycji obszaru obliczeniowego do rozwiązania równań Naviera-Stokesa sformułowanych w postaci wirowość-funkcja prądu
Autorzy:
Bogusławski, A.
Kubacki, S.
Powiązania:
https://bibliotekanauki.pl/articles/280218.pdf
Data publikacji:
2009
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
spectral methods
domain decomposition method
influence matrix technique
Opis:
The paper presents new multi-domain algorithms based on the influence matrix technique applied together with the non-overlapping iterative domain decomposition method for solution of the incompressible Navier- Stokes equations in vorticity-streamfunction formulation. The spectral Chebyshev collocation method and the influence matrix algorithm are applied for solution of the Stokes problem in each subdomain resulting from time discretization of the Navier-Stokes equations, while the patching conditions (continuity of the solution and continuity of its first order derivative) at the interfaces between subdomains are satisfied using the iterative domain decomposition algorithm.
W pracy przedstawiono nowy iteracyjny algorytm dekompozycji obszaru obliczeniowego oparty na metodzie macierzy wpływu w zastosowaniu do równań Naviera- -Stokesa dla przepływu czynnika nieściśliwego w sformułowaniu wirowość-funkcja prądu. Spektralna metoda kolokacji wykorzystująca szeregi wielomianów Czebyszewa oraz metoda macierzy wpływu została zastosowana do rozwiązania zagadnienia Stokesa, będącego rezultatem dyskretyzacji równań Naviera-Stokesa w funkcji czasu, w każdym z podobszarów obszaru obliczeniowego, natomiast warunek ciągłości rozwiązania i jego pierwszej pochodnej na powierzchniach rozdziału pomiędzy podobszarami został uzyskany przy pomocy metody iteracyjnej.
Źródło:
Journal of Theoretical and Applied Mechanics; 2009, 47, 1; 17-40
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Novel analytic-numerical model of free convection: with leading edge considered
Autorzy:
Leble, S.
Lewandowski, W. M.
Powiązania:
https://bibliotekanauki.pl/articles/1954434.pdf
Data publikacji:
2022-02-01
Wydawca:
Politechnika Gdańska
Tematy:
Navier-Stokes equations
Fourier-Kirchhoff equations
free convection
heat transfer
isothermal surface
boundary layer
vertical plate
leading edge
Równania Naviera-Stokesa
równanie Fouriera-Kirchhoffa
przenikanie ciepła
izoterma powierzchni
warstwa graniczna
płyty pionowe
Opis:
A novel solution of the free convection boundary problem is represent ed in analytical form for velocity and temperature for an isothermal vertical plate, as an example. These fields are built as a Taylor Series in the x coordinate with coefficients as functions of the vertical coordinate (y). We restrict ourselves by cubic approximation for both functions. The basic Navier-Stokes and Fourier-Kirchhoff equations and boundary conditions give links between coefficients and connected with free convection heat transfer phenomen on which define the analytical form of the solution as a function of the Grashof number only. In t he solution the non zero velocity of a fluid flow through a leading edge of the plate is take n into account. The solution in the form of velocity and temperature profiles is numerically evaluated and illustrated for air.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2014, 18, 2; 167--185
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of Waterloo MAPLE 9.5 and Wolfram MATHEMATICA 5.1 software for analytic solving of certain nonlinear partial differential equations of physics
Zastosowanie pakietów MAPLE 9.5 oraz MATHEMATICA 5.1 do analitycznego rozwiązywania wybranych nieliniowych równań różniczkowych cząstkowych fizyki
Autorzy:
Stępień, Ł.T.
Powiązania:
https://bibliotekanauki.pl/articles/952947.pdf
Data publikacji:
2008
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
nieliniowe równania różniczkowe cząstkowe
rozwiązania analityczne
rozwiązania dokładne
równanie Naviera-Stokesa
równanie Monge'a-Ampere'a
równanie stałego przepływu izentropowego
nonlinear partial differential eguations
analytic solutions
exact solutions
Navier-Stokes eguation
Monge-Ampere eguation
steady isentropic flow eguation
Opis:
In the current paper some applications of the packet MAPLE (v. 9.5) for analytic solying of certain nonline partial differential eguations have been presented. Additionally, for graphic presentation of the found solutions packet MATHEMATICA (v. 5.1) has been applied.
W niniejszej pracy zostały przedstawione zastosowania pakietu MAPLE (wersja 9.5 do analitycznego znajdywania rozwiązań wybranych nieliniowych równań różniczkowych cząstkowych. Do prezentacji graficznej tych rozwiązań użyto pakietu MATHEMATICA (wersje 5.1).
Źródło:
Computer Science; 2008, 9; 147-155
1508-2806
2300-7036
Pojawia się w:
Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
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