显式滤波大涡模拟算法

Large-Eddy Simulation with Explicit Filtering

在传统大涡模拟算法的基础上引入显式滤波技术,有效地控制了截断误差.对对流项和湍流应力项进行二次显式滤波,并对湍流应力的分解形式作了相应改进.以三维平板通道为计算模型编写了二阶精度计算程序,对传统、显式滤波大涡模拟2种算法的计算结果进行了对比,并就亚滤波模型的重建程度对计算精度的影响进行了探讨.计算结果表明:2种算法对流线方向平均速度分布模拟差异不大,但显式滤波大涡模拟算法可明显改进脉动速度分布;随着对亚滤波模型重建程度的提高,平均速度和脉动速度分布均有明显改进.

Turbulent 3-D channel flow simulations were performed with second-order finite difference codes. Explicit filtering was used to control truncation error. A second filtering was applied to the convective and turbulent stress terms, and a new separation of the turbulent stresses was proposed. The data with explicit filtering were compared with the results from the traditional large eddy simulation approach. The dynamic Smagorinsky model, the dynamic mixed model and the dynamic reconstruction model were also discussed. Our findings show that, for the two algorithms, the difference in the mean velocity profile is not large, however, the fluctuation velocities are improved for the explicit filtering case. On the other hand, increasing the reconstruction levels for the resolved subfilterscale stress improves the mean velocity and the fluctuation velocities.