平面突扩流动非稳定性的大涡模拟

Simulation of unsteady flow in plane sudden expansion by LES

用ＴＧ有限元法求解二维大涡模拟的非定常Ｎ－Ｓ方程，数值模拟了平面突扩流动，计算结果展示了回流区内流动的多涡结构及其不稳定的周期振荡过程，而该振荡过程的周期时间历程平均，恰好与诸多湍流模型的计算结果及实验结果相吻合，证明了数值模拟的正确性。

The transient N S equation filtered by LES method is solved to simulate plane sudden expansion flow. The numerical results show that there are more than one vortex in reattaching region, and the vortexes are unsteady, which makes the flow in the reattaching region oscillate periodically. But the average result over time in one oscillating period gives one perfect vortex which agrees very well with other numerical results. It is proved that the numerical simulation is correct.