Abstract: A new version of RANS/LES hybrid method with the entropy function fs as the blending function is proposed to avoid the dependence on the grid. Three test cases including supersonic turbulent boundary-layer flow，supersonic cavity-ramp flow and supersonic base flow are chosen to evaluate its performance. The results of the original detached-eddy simulation (DES97) are also included for comparison. It shows that turbulent boundary-layer region is reliably denoted by fs for both attached and separated flows. Compared by the results of DES97，the modeled stress depletion (MSD) phenomenon induced by refined grid is largely suppressed without loss of LES content after massive separation. Moreover，fs is deduced from the point of energy dissipation，independent of any particular turbulent quantities. That is，this entropy function could be utilized by other RANS/LES strategies.

Key words: Hybrid method；Detached-eddy simulation；Entropy；Computational fluid dynamics

摘要： 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。

关键词: 混合方法；脱体涡模拟方法；熵；计算流体力学