再冲击载荷作用下流动混合的数值模拟

Numerical simulation of flow mixing impacted by reshock

基于多介质的流体体积分数VOF(volume of fluid)方法和PPM(piecewise parabolic method)方法,给出和发展了可用于多介质粘性流体动力学的数值计算方法和计算代码MVPPM(multi-viscosity-fluidpiecewise parabolic method)。为了检验和验证此计算代码,对某激波管实验——再冲击载荷作用下的流体动力学不稳定性及其导致的混合过程进行了数值模拟,计算结果与实验结果一致。同时还研究了激波反射冲击作用下流体混合区的演化情况,在反射激波和混合区相互作用的瞬间,混合区的宽度明显减小,之后又迅速增大;另外,混合增长率与初始扰动的频谱有很大关联。通过对有粘性(分子动力学粘性)和无粘性结果的对比,发现粘性对混合区的影响很小。

On the basis of the multi-fluid volume-of-fraction method and piecewise parabolic method, a multi-viscosity-fluid piecewise parabolic method（MVPPM） was proposed and the corresponding computer code was developed to investigate the multi-viscous-fluid dynamic problems. To verify and validate the developed code, a shock tube experiment of hydrodynamic instability and flow mixing induced by reshock was simulated numerically. The numerical results are in agreement with the experimental results. The evolution of the fluid mixing zone under reshock reveals that the mixing growth rate has a close dependence on the spectra and amplitudes of the initial perturbation, and at the moment the reshock arrives at and interacts with the interface, the fluid mixing zone width decreases sharply, then increases quickly again. Comparison between viscous and inviscid results displays that the molecular dynamics viscosity affects weakly on the fluid mixing zone.