近水面水下爆炸二维Level-set数值模拟

水下爆炸是一个多介质、动边界、瞬态非线性过程,捕捉介质之间交界面的变化是数值模拟的一个难点.本文采用Level-set方法来描述水下爆炸气体产物和流体交界面以及自由表面变化,应用TVD (Total Variation Diminishing) 计算技术求解Level-set流场,首先建立了近水面水下爆炸的二维数值方法,然后,将该方法推广到流场内有刚性结构的情况,考虑了冲击波和刚性结构物的相互作用.为了模拟无限边界流场问题,引进了Thompson建立的无反射边界条件.

2D numerical simulation of underwater explosion nearfree surface based on level-set method

The problem of underwater explosion near free surface is a dynamic process involving multi-medium and transient nonlinearity. The dominant difficulty is how to trace the moving interface between different medium. The level-set technique is adopted herein to capture the time-dependent changes of the free surface and the moving interface of explosive gaseous product and water. To simulate compressible-fluid flow in which discontinuous shocks are present, the high-resolution method of Total Variation Diminishing (TVD) scheme is used. A numerical method has been first developed for numerical simulation of 2-D underwater explosion near free surface. The method is then extended to account for the interaction of fluid and a rigid structure present in water. The non-reflection boundary condition technique developed by Thomson is finally employed for considering the infinite flow field.