后台阶流动的Hybrid RANS/LES模拟  

Hybrid RANS-LES method applied to backward facing step flow

作　　者：吴晶峰[1] 宁方飞[1] 

机构地区：[1]北京航空航天大学能源与动力工程学院,北京100191

出　　处：《北京航空航天大学学报》2011年第6期701-704,共4页Journal of Beijing University of Aeronautics and Astronautics

基　　金：国家自然科学基金资助项目(50506001)

摘　　要：采用雷诺平均的Navier-Stokes和大涡模拟混合的方法对后台阶流动进行了数值模拟,并与实验结果进行了对比;分区尺度采用IDDES(Improved Delayed Detached Eddy Simulation)模式:来流包含背景湍流度时,混合方法转化为WMLES(Wall Modeling in LES)模拟,除了近壁区外的大部分区域都是直接求解;不包含来流湍流度时,转化为DDES(Delayed Detached Eddy Simulation)模式,附面层采用纯RANS模拟,大分离流动区用类脱体涡模拟方法模拟;对流通量的离散采用迎风型低耗散通量分裂格式和中心型四阶偏斜对称格式组合的模式;湍流模型采用Spalart-Allmaras(S-A)模型;亚格子长度尺度取决于网格分布和到壁面的距离.Turbulent flow over a backward facing step was simulated using a hybrid Reynolds averaged navier stokes （RANS）-large eddy simulation（LES） approach, and the results were compared with experimen- tal data. The hybrid system combines delayed detached-eddy simulation （DDES） with an improved RANSLES hybrid model aimed at wall modeling in LES （WMLES）. It ensures a different response depending on whether the simulation has inflow turbulent content. In the case of with inflow turbulent content, the WMLES branch of the system is active： most of the turbulent is resolved expect the flow near the wall. In the other case, the DDES branch of the system is active,i, e. , it gives a pure RANS solution for attached flows and a DES-like solution for massively separated flows. In the system, a scheme which combines the upwind low-diffusion flux-splitting scheme and fourth-order skew-symmetric scheme was used as the convective flux scheme. The spalart-allmaras （S-A） model was applied as a subgrid scale （SGS） model. The definition of the subgrid length-scale was new which depends not only on the grid spacing, but also on the wall distance.

关 键 词：后台阶流 脱体涡模拟 对流格式 

分 类 号：V211.1[航空宇航科学与技术—航空宇航推进理论与工程]