Inverse Lax-Wendroff procedure for numerical boundary conditions of convection-diffusion equations

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• 作者：Jianfang Lu^a ; ^{kobey@mail.ustc.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Jinwei Fang^b ; ^{gerrard.fang@gmail.com" class="auth_mail" title="E-mail the corresponding author} ; Sirui Tan^c ; ^{sirui_tan@alumni.brown.edu" class="auth_mail" title="E-mail the corresponding author} ; Chi-Wang Shu^c ; ¹ ; ^{shu@dam.brown.edu" class="auth_mail" title="E-mail the corresponding author} ; Mengping Zhang^a ; ² ; ^{mpzhang@ustc.edu.cn" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Convection&ndash ; diffusion equation ; High order finite difference methods ; Numerical boundary condition ; Inverse Lax&ndash ; Wendroff method ; Compressible Navier&ndash ; Stokes equations
• 刊名：Journal of Computational Physics
• 出版年：2016
• 出版时间：15 July 2016
• 年：2016
• 卷：317
• 期：Complete
• 页码：276-300
• 全文大小：940 K

文摘

We consider numerical boundary conditions for high order finite difference schemes for solving convection–diffusion equations on arbitrary geometry. The two main difficulties for numerical boundary conditions in such situations are: (1) the wide stencil of the high order finite difference operator requires special treatment for a few ghost points near the boundary; (2) the physical boundary may not coincide with grid points in a Cartesian mesh and may intersect with the mesh in an arbitrary fashion. For purely convection equations, the so-called inverse Lax–Wendroff procedure [28], in which we convert the normal derivatives into the time derivatives and tangential derivatives along the physical boundary by using the equations, has been quite successful. In this paper, we extend this methodology to convection–diffusion equations. It turns out that this extension is non-trivial, because totally different boundary treatments are needed for the diffusion-dominated and the convection-dominated regimes. We design a careful combination of the boundary treatments for the two regimes and obtain a stable and accurate boundary condition for general convection–diffusion equations. We provide extensive numerical tests for one- and two-dimensional problems involving both scalar equations and systems, including the compressible Navier–Stokes equations, to demonstrate the good performance of our numerical boundary conditions.