3维Mortar谱元法模拟Kelvin-Helmhtz不稳定性混合层

Simulation of Kelvin-Helmhtz instability with three-dimensional Mortar spectral element method

采用Mortar谱元法和多处理器并行计算技术模拟了Kelvin-Helmhtz界面不稳定性湍流的混合发展过程,通过对混合层动量厚度、能谱和总动能的计算,评估了Kelvin-Helmhtz混合层的演化机理。计算结果表明:3维Mortar谱元法具有高计算精度和光滑区域的指数收敛特性,可以有效模拟混合层流动的湍流混合和演化,能够捕捉到涡的合并现象和大涡到小涡的级联过程;初期的混合层层流运动发展成具有连续谱结构的湍流运动过程,实现了Kelvin-Helmhtz界面不稳定性混合层流动从2维发展到3维的转捩特征,总湍流统计动能的变化反映了粘性耗散过程的作用。通过对Kelvin-Helmhtz 3维界面不稳定性混合层流动和3维层流向湍流转捩过程的数值模拟,程序的有效性得到了验算,表明谱元法应用于湍流混合模拟是可行的。

The Mortar spectral element method and message passing interface（MPI） parallel computation technique have been used in studying turbulent mixing of Kelvin-Helmhtz instabilities, and the evolution mechanism of Kelvin-Helmhtz instabilities has been estimated with the calculation of momentum thickness, energy spectrum and total kinetic energy. The results show that, the three-dimensional Mortar spectral element method can effectively capture the turbulent mixing of Kelvin Helmhtz instability, with cascading and combination of turbulent eddies clearly shown. In addition, the initial laminar fluid flow of Kelvin- Helmbtz instability gradually developed into a turbulent flow with continuous spectrum structure in the simulation, thus two- dimensional to three-dimensional transition can be achieved. The statistical turbulent kinetic energy reflects the viscous dissipation of the turbulent mixing. The validity of the spectral element code has been demonstrated, and the feasibility of the spectral.