基于非结构/混合网格的脱体涡模拟算法

Detached-eddy simulation based on unstructured and hybrid grid

为了提高二阶精度有限体积算法的湍流数值模拟能力,在原始Roe格式基础上建立了与脱体涡模拟(DES)方法相匹配的二阶混合耗散自适应格式,根据流场信息自动调节格式耗散,并分别基于Spalart-Allmaras一方程湍流模型和k-ω剪切应力输运(SST)两方程湍流模型,发展了基于非结构/混合网格的DES方法。采用该方法计算了雷诺数为3 900的圆柱绕流和NACA 0021翼型60°大迎角分离流两个典型算例,通过与试验数据以及其他数值结果的对比验证了该方法的可行性。同时开展了不同数值格式、湍流模型的对比分析,研究结果表明:采用混合格式的DES算法能够解析更小尺度的湍流涡结构、计算数据更接近试验值;本文的DES类算法受其基准湍流模型影响较小。

To improve the turbulence simulation ability of the second order finite-volume algorithm based on unstructured and hybrid grid, a hybrid second order scheme is established by modifying the dissipation term of the standard Roe flux-difference splitting scheme and the numerical dissipation of the scheme can be self-adapted according to the detached-eddy simu- lation （DES~ flow field information. The credibility of the approach is supported by two typical numerical examples of its application： Re=3 900 circular cylinder and NACA 0021 airfoil at high angle of attack （60°）, and the DES predictions are compared with experimental data and with other numerical solutions. The DES methods based on both the one equation Spalart-AIImaras turbulence model and the two equation k-ω shear stress transport （SST） model are used in the computation. The effects of numerical schemes and turbulence models are also discussed in the study, which shows that the scale of turbulence structure resolved by the hybrid scheme is smaller than that resolved by the standard Roe scheme and the corresponding flow field is better; meanwhile the DES methods used in this paper are little affected by their RANS-based models.