共查询到20条相似文献，搜索用时 0 毫秒
1.
We design an artificial boundary condition for the steady incompressible Navier–Stokes equations in streamfunction–vorticity formulation in a flat channel with slip boundary conditions on the wall. The new boundary condition is derived from the Oseen equations and the method of lines. A numerical experiment for the non-linear Navier–Stokes equations is presented. The artificial boundary condition is compared with Dirichlet and Neumann boundary conditions for the flow past a rectangular cylinder in a flat channel. The numerical results show that our boundary condition is more accurate. 相似文献
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W. Drfler O. Goncharova D. Krner 《ZAMM - Journal of Applied Mathematics and Mechanics / Zeitschrift für Angewandte Mathematik und Mechanik》2002,82(3):167-176
A liquid at rest in a container will show a contact angle at the wall depending on material properties. If the liquid, or the boundary walls, are moving with constant speed, this angle will change with velocity. We perform numerical experiments for a two‐dimensional model free boundary value problem that has been proved to be well‐posed and show that the dependence of the contact angle on the velocity is qualitatively correct. 相似文献
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We present a numerical scheme to solve the incompressible Navier–Stokes equations with open boundary condition. After replacing the incompressibility constraint by the pressure Poisson equation, the key is how to give an appropriate boundary condition for the pressure Poisson equation. We propose a new boundary condition for the pressure on the open boundary. Some numerical experiments are presented to verify the accuracy and stability of scheme. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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This paper presents a novel meshless Galerkin scheme for modeling incompressible slip Stokes flows in 2D. The boundary value problem is reformulated as boundary integral equations of the first kind which is then converted into an equivalent variational problem with constraint. We introduce a Lagrangian multiplier to incorporate the constraint and apply the moving least‐squares approximations to generate trial and test functions. In this boundary‐type meshless method, boundary conditions can be implemented exactly and system matrices are symmetric. Unlike the domain‐type method, this Galerkin scheme requires only a nodal structure on the bounding surface of a body for approximation of boundary unknowns. The convergence and abstract error estimates of this new approach are given. Numerical examples are also presented to show the efficiency of the method. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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A new artificial boundary condition for two‐dimensional subsonic flows governed by the compressible Navier–Stokes equations is derived. It is based on the hyperbolic part of the equations, according to the way of propagation of the characteristic waves. A reference flow, as well as a convection velocity, is used to properly discretize the terms corresponding to the entering waves. Numerical tests on various classical model problems, whose solutions are known, and comparisons with other boundary conditions (BCs), show the efficiency of the BC. Direct numerical simulations of more complex flows over a dihedral plate are simulated, without creation of acoustic waves going back in the flow. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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Liu Xi-yun 《应用数学和力学(英文版)》1994,15(3):229-234
In this paper, the domain integral of the form of Poisson equation is translated into complete boundary integral by the fundamental solution of higher-order Laplace operator, the dimensions of the problem can be contracted into one. The numerical examples for Stokes equations show that this method is efficient. 相似文献
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Daniele A. Di Pietro 《国际流体数值方法杂志》2007,55(8):793-813
In this work, we propose and analyse a discontinuous Galerkin (DG) method for the Stokes problem based on an artificial compressibility numerical flux. A crucial step in the definition of a DG method is the choice of the numerical fluxes, which affect both the accuracy and the order of convergence of the method. We propose here to treat the viscous and the inviscid terms separately. The former is discretized using the well‐known BRMPS method. For the latter, the problem is locally modified by adding an artificial compressibility term of the form (1/c2)(?p/?t) for the sole purpose of interface flux computation. The flux is obtained as the exact solution of a local Riemann problem. The analysis of the method extends the well‐established strategies for the DG discretization of the Laplacian to the resulting partially coercive problem. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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刘希云 《应用数学和力学(英文版)》1994,(3)
ＳＯＬＵＴＩＯＮＴＯＴＨＥＦＯＲＭＯＦＰＯｌＳＳＯＮＥＱＵＡＴＩＯＮＢＹＴＨＥＢＯＵＮＤＡＲＹＥＬＥＭＥＮＴＭＥＴＨＯＤＳＬｉｕＸｉ－ｙｕｎ（刘希云）（ＮａｎｊｉｎｇＵｎｉｖｅｒｓｉｔｙｏｆｓｃｉｅｎｃｅａｎｄＴｅｃｈｎｏｌｏｇｙ）Ｎａｎｊｉｎｇ（Ｒ... 相似文献
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From the point of view of energy analysis,the cause that the uniqueness of theboundary integral equation induced from the exterior Helmholtz problem does not hold isinvestigated in this paper.It is proved that the Sommerfeld’s condition at the infinity ischanged so that it is suitable not only for the radiative wave but also for the absorptive wavewhen we use the boundary integral equation to describe the exterior Helmholtz problem.Therefore,the total energy of the system is conservative.The mathematical dealings toguarantee the uniqueness are discussed based upon this explanation 相似文献
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Hela Louati Mohamed Meslameni Ulrich Razafison 《ZAMM - Journal of Applied Mathematics and Mechanics / Zeitschrift für Angewandte Mathematik und Mechanik》2020,100(6):e201900181
We study the three-dimensional stationary exterior Stokes problem with non standard boundary conditions corresponding to a slip-without-friction boundary conditions. Because the flow domain is unbounded, we set the problem in weighted spaces in order to control the behavior at infinity of solutions. This functional framework allows to prescribe various behaviors at infinity of the solutions. The established results are related to the existence and the uniqueness of strong and very weak solutions. Our strategy relies on the fact that due to the boundary conditions, the pressure and the velocity can be decoupled and, as a result, we solve two separate systems to find these quantities. 相似文献
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Oscillating boundary layer flow over an infinite flat plate at rest was simulated using the k–kL–ω turbulence model for a Reynolds number range of 32 ⩽ Reδ ⩽ 10,000 ranging from fully laminar flow to fully turbulent flow. The k–kL–ω model was validated by comparing the predictions with LES results and experimental results for intermittently turbulent and fully turbulent flow regimes. The good agreement obtained between the k–kL–ω model prediction with the experimental and LES results indicate that the k–kL–ω model is able to accurately simulate transient intermittently turbulent flow and as well as accurately predict the onset of turbulence for such oscillatory flows. 相似文献
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Yang Zuosheng 《国际流体数值方法杂志》2005,47(12):1423-1430
A complete boundary integral formulation for compressible Navier–Stokes equations with time discretization by operator splitting is developed using the fundamental solutions of the Helmholtz operator equation with different order. The numerical results for wall pressure and wall skin friction of two‐dimensional compressible laminar viscous flow around airfoils are in good agreement with field numerical methods. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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证明平面调和函数的Dirichlet外问题解存在唯一的充要条件;在此基础上,建立Laplace和Poisson外问题的等价边界积分方程;通过实例对传统的边界积分方程进行了讨论,表明它们不具有普遍适用性. 相似文献
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M. T. Manzari 《国际流体数值方法杂志》2012,68(7):905-921
A modified weakly compressible smoothed particle hydrodynamics (WCSPH) is presented, which utilizes consistent discretization schemes for spatial derivatives in the flow equations. Here, each SPH particle is considered as a computational point that represents a specific part of the fluid. To overcome non‐physical oscillations that usually arise in standard WCSPH, we modified the mass conservation equation by using a numerical filter. This modification is based on the difference between two discretization schemes used for the term . Furthermore, a new implementation of wall boundary condition in SPH is introduced. This condition is imposed on the pressure of wall boundary particles to ensure that the acceleration of each boundary particle in normal direction to the wall is zero. Thus, no penetration through walls will occur. To examine the performance of the modified method, we solved a series of two‐dimensional incompressible internal flow benchmark problems. By comparing the result with analytical solutions and the results of the standard WCSPH, we show that the use of consistent schemes in conjunction with the proposed numerical filter improves both accuracy and speed of the numerical method. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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We propose a novel fitted finite element method for two‐phase Stokes flow problems that uses piecewise linear finite elements to approximate the moving interface. The method can be shown to be unconditionally stable. Moreover, spherical stationary solutions are captured exactly by the numerical approximation. In addition, the meshes describing the discrete interface in general do not deteriorate in time, which means that in numerical simulations, a smoothing or a remeshing of the interface mesh is not necessary. We present several numerical experiments for our numerical method, which demonstrate the accuracy and robustness of the proposed algorithm. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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连广昌 《应用数学和力学(英文版)》1986,7(12):1203-1221
An aerofoil above which is built the artificial cavity low pressure region is called\"cavitating airfoil\".By using generalized Blasius’s theorem and conformal transformation,this paper investgates the problem of the flow past the aerofoil of cavitatting airfoil with thejetstream above cavitation,and gives the formulae of the lift and thrust. 相似文献