基于非结构动网格的非定常激波装配法

An unsteady shock-fitting technique based on unstructured moving grids

从ALE方程出发,通过修正体积的新思路构建离散几何守恒律,基于非结构动网格的信息传递方法得到网格重构以后新网格的流场参数,采用一阶格式捕捉法得到的流场确定装配法的初始激波位置,成功地把激波装配法应用到非定常流动的模拟。模拟超声速飞行环境下整流罩分离的非定常流固耦合过程,在马赫数6条件下装配法和捕捉法的计算结果完全一致,随着马赫数增加,二阶精度格式的捕捉法需要进行调整限制器参数、时间步长等人工干预,但是装配法直到马赫数20计算过程没有出现异常。该基于非结构动网格技术的激波装配方法,与传统的激波装配方法相比,能够用于复杂外形产生的非规则形状激波和非定常流动产生的运动激波,解决二阶精度有限体积法用于高马赫数飞行条件下多体分离过程的流动模拟时遇到的稳定性问题。

A shock-fitting technique based on unstructured moving grids is developed.Based on Arbitrary Lagrangian-Eulerian （ALE ） equations, Discrete Geometric Conservation Law （DGCL）is constructed by adopting a new idea for modifying the volume;the field variables of new re-meshing grids are obtained by the information transfer method based on the unstructured moving grids technique;the initial shock position is determined by the flow field captured by the first-order spatial scheme and the unsteady flow is successfully simulated using shock-fitting tech-nique.The fluid-structure coupled process of hypersonic fairing separation when Mach number reaches 6.0 is simulated using the shock-fitting and shock-capturing methods respectively,and the simulation results are good in agreement.With Mach number increased,the accuracy is hard to reach second-order unless by adjusting the limiter parameters or time step artificially.Howev-er,there is no abnormal occurring even if the Mach number reaches to 20.0 when the shock-fit-ting method is adopted.Comparing with the traditional shock-fitting technique,the unsteady shock-fitting technique can be used to simulate the irregular shock produced by complex shapes and the moving shock wave produced by the unsteady flow,it can also solve the stability problem which may generally occurred in the process of simulating the multi-body separation by the finite volume method （FVM ）.