以DES类方法为代表的RANS-LES混合方法，在圆柱类钝体/机翼大迎角、三角翼涡破裂、后台阶/空腔、建筑尾迹等流动的模拟取得了一定的成功。然而，现有的DES类方法在模拟翼型尾缘中小分离、超音速底部、浅后台阶/空腔等非定常较弱的分离流动时，表现出RANS到LES转换延迟的“灰区”问题，抑制剪切层的失稳和发展，推迟流动的分离及涡的破裂。前人研究表明，改进DES类方法中LES分支的长度尺度，考虑计算网格的非各向同性及分离剪切湍流的各向异性，是改善DES方法的一条重要途径。.本项目拟以DDES方法为基础，引入网格非各向同性修正及基于相干结构函数自适应变化系数CDES，改善原方法在计算非定常较弱的分离流动时的“灰区”问题，发展既能较好的模拟非定常大分离问题，也能模拟好非定常较弱的中小分离问题，且高效、鲁棒的新DDES方法，更好的为工业领域中涉及的复杂外形的分离流动服务。

The RANS-LES hybrid methods such as DES methods, have achieved some success in the simulations of massively separated or vortex breakdown flows around blunt bodies as cylinders and wings at high incidence, delta wings, backward-facing steps, cavities and buildings. However, the present DES methods exhibit “grey area” problems for slightly unsteady separation such as mild or moderate trailing-edge separation around airfoils, supersonic base flows and shallow backward-facing steps or cavities. The “grey area” may inhibit the instability and evolution of shear-layer, even postpone the separation and vortex breakdown. Previous studies show that improvement of the length scale of LES branch in the DES methods, for instance, taking account of the anisotropy of the computational grids and turbulent shear-layer, may be an effective manner to enhance the performance of DES methods. .In this project, the “grey area” of the DDES for slightly unsteady separation would be alleviated by introducing the correction of anisotropic grid and the self-adaption of the coefficient CDES. The new DDES model is expected to be suitable for unsteady massive separation as well as mild separation, and robust for separated flows around complex configurations in industry.