二维多介质流动问题的界面处理方法

就二维可压缩多介质流动问题的数值模拟，给出了一种新的界面处理方法。通过在界面处构造Riemann问题,利用Riemann问题的解分别定义界面两边流体的边界条件，由于Riemann问题的解准确地描述了界面处流体的流动状态，因此得到了更加准确的界面边界条件。本文将由Riemann问题的解得到的界面速度外推到整个流场，重新定义速度场，避免了由于速度的大梯度变化而导致的Level—Set等值线相互交错，因而得到了更加精确的界面位置。利用该方法对水下激波与柱型气泡相互作用问题进行数值模拟，结果表明该方法能准确地捕捉各种物理现象。

Interface Treating Method for 2-D Multi-Medium Flow

A new interface treating method is used for 2-D multi - medium flow. The Riemann problems are constructed on the interface and solved to define the boundary conditions for fluid on both sides of the interface, respec tively. As Riemann problem solvers describe the fluid states reasonably, a more accurate interface boundary condition is obtained. In order to overcome the diff iculties associated with the severe bunching of level set contours due to the la rge flow velocity gradient, an extension velocity field is constructed by the co mputation of level set function. The new method is used to simulate the underwat er shock-bubble interaction problem. Results show that the method can correctly capture the physics phenomenon.