Improvements on the detached eddy simulation for supersonic mixing layers

The series of detached eddy simulation (DES) methods are widely used in computational fluid dynamics simulations. One of the current problems of DES is the inaccuracy in free shear flows, which may lead to the problem of the slow development of mixing layers. Researches show that the large eddy simulation (LES) often provides more accurate results than DES. In this paper, contrastive studies are made on an experimental supersonic mixing layer between DES with different model definitions and LES. According to the numerical results, DES delays the development of the mixing layer compared to LES and the experiment. Furthermore, studies also show that the modified definitions of the length scale and the subgrid eddy viscosity coefficient would both help to improve the performance of DES methods. Necessary theoretical analyses are made to explain the model difference of the LES mode of DES and the Smagorinsky-LES.