Speaker: Prof. Zhijun Shen（沈智军教授）

Time: 9:00-10:00, 5 November 2025 (Wednesday)  (Beijing time)

Venue: A103, Lijiao Building, BNU Zhuhai

Abstract

This paper investigates solution behaviors of the cell-centered Lagrangian method under the strong shock interaction. It is well known that the Lagrangian method is easy to suffer from nonphysical grid tangling in multidimensional calculations. In order to unveil the cause of producing these failings, some classical and newly proposed Riemann solvers are reviewed on a moving mesh. By comparing different type viscosities, the relations between the shock instability and mesh tangling are discussed.  The observation shows that the dissipation on shear wave is a very important factor to cause mesh tangling, while compatibility between the grid moving manner and numerical flux is not indispensable in stabilizing computation. Furthermore, a heuristic analysis based on the Lagrangian method is proposed to illustrate the effect of shear viscosity. A specific viscosity associated to the shear wave provides a dissipative mechanism to reduce the vorticity errors. A robust and contact resolving Riemann solver is recommended to be used in the cell-centered Lagrangian method.

About the Speaker

沈智军，男，北京应用物理与计算数学研究所研究员，北京大学工学院兼职研究员， 博士生导师。本科毕业于浙江大学数学系，博士毕业于中国工程物理研究院研究生部。长期从事中子输运方程、辐射扩散方程和流体力学方程组的数值方法 研究。曾两次荣获国防科工委科技进步二等奖，历任北京计算数学学会理事、常务理事;中国计算数学学会理事、常务理事;中国数学会理事; 担任过教育部科技管理信息系统专家组成员;现为中国科协智慧科技人才评审专家成员。主持国家自然科学基金 NSFA 联合基金重点项目一项和多项国家基金面上项目;作为子课题负责人主持国防基础科研核科学挑战专题子课题和国家某重大专项子课题。在包括 J. comput. Phy., SIAM. Sci. Comput. 等重要期刊上发表 SCI 论文六十余篇。