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为解决RANS/LES混合方法过渡依赖网格疏密的问题,使用熵函数fs作为交界面函数构造一种新型的动态RANS/LES混合方法。同时采用脱体涡模拟方法 (DES97),对平板边界层流动、超声速凹腔-压缩拐角流动以及超声速底部流动进行数值模拟,并与实验数据进行对比。结果表明,无论对于附体流动区域还是分离区域,fs都能够动态地指示出边界层的范围。构造的动态RANS/LES混合方法能够显著缓解DES97由于网格因素导致的雷诺应力模化不足的现象,同时保证分离区域涡结构的求解精度。另外,熵函数fs是从能量耗散的角度进行构造,并不依赖于特定的湍流变量,因此更具有普适性。
In order to solve the problem that the RANS / LES hybrid method depends on the transition of grid density, a new dynamic RANS / LES hybrid method is constructed by using the entropy function fs as the interface function. At the same time, using DES 97, the numerical simulation of plate boundary layer flow, supersonic cavity-compression corner flow and supersonic bottom flow was carried out and compared with the experimental data. The results show that fs can indicate the range of the boundary layer dynamically both for the attachment flow area and the separation area. The dynamic RANS / LES hybrid method can significantly alleviate the Renault stress moderation caused by the mesh factor of DES97, and ensure the accuracy of the vortex structure in the separation area. In addition, the entropy function fs is constructed from the viewpoint of energy dissipation and does not depend on a specific turbulence variable, so it is more universal.