高雷诺数槽道湍流的壁面模化大涡模拟研究

选取基准壁湍流的槽道流动,研究了多种模型的壁面模化大涡模拟.模型包括经典的大涡模拟、Spalart-Allmaras、分离涡模拟和一种动态混合模型.基于摩擦速度的雷诺数范围为395~12000,采用3组粗糙网格,流向和展向维数分别同取37,49和65,法向维数保证y+(1)~1.主要研究平均速度、雷诺切应力分布、详细分析了各模型的特性差异并展示了相应的湍流结构.研究表明:在高雷诺数粗糙网格下,大涡模拟失去求解精度,分离涡模拟出现对数律不匹配,动态混合模型的计算接近直接数值模拟,其对数率区可解应力约占雷诺切应力的93%,边界层外层可解应力约占99%.这说明合适的混合模型可以在经济成本下保证计算精度,具有解决实际问题的潜力. 

Investigation on wall modeled large eddy simulation of channel turbulent flow in high Reynolds number

The numerical simulation of plane channel flow was performed with various turbulent models, which were employed for wall modeled large eddy simulation. Large eddy simulation (LES), Spalart-Allmaras (S-A), detached eddy simulation (DES) and a dynamic hybrid model (Hybrid) were investigated. Using the Reynolds numbers ranging from 395 to 12000 based on friction velocity, three kinds of coarse grid were used, the grid numbers of wall-parallel directions were set as 37, 49 and 65, simultaneously.y⁺ (1)~1 was maintained in wall-normal direction. Mean velocity profile, Reynolds-shear stress and other turbulent statistics were predicted. It was shown that LES cannot provide accurate solutions at high Reynolds number and coarse grid conditions. Log layer mismatch was still a problem of DES. The simulation of Hybrid agreed well with direct numerical simulation (DNS), and the resolved stress accounted for 93% in log layer and about 99% in outer layer. Therefore, proper hybrid model may provide accurate solutions with cost effectiveness and has potential to solve engineering problem.