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 引用本文: 时北极, 何国威, 王士召. 基于滑移速度壁模型的复杂边界湍流大涡模拟[J]. 力学学报, 2019, 51(3): 754-766.
Beiji Shi, Guowei He, Shizhao Wang. LARGE-EDDY SIMULATION OF FLOWS WITH COMPLEX GEOMETRIES BY USING THE SLIP-WALL MODEL[J]. Chinese Journal of Theoretical and Applied Mechanics, 2019, 51(3): 754-766.
 Citation: Beiji Shi, Guowei He, Shizhao Wang. LARGE-EDDY SIMULATION OF FLOWS WITH COMPLEX GEOMETRIES BY USING THE SLIP-WALL MODEL[J]. Chinese Journal of Theoretical and Applied Mechanics, 2019, 51(3): 754-766.

## LARGE-EDDY SIMULATION OF FLOWS WITH COMPLEX GEOMETRIES BY USING THE SLIP-WALL MODEL

• 摘要: 采用滑移速度壁模型实现了浸入边界方法与壁模型相结合的大涡模拟.本文首先分别采用平衡层模型和非平衡壁模型对周期山状流进行数值模拟,以考查在壁模型中考虑切向压力梯度的作用.数值结果表明,流场的压力对本文所采用的壁模型形式并不敏感,但是考虑切向压力梯度可以显著改进壁面摩擦力的计算结果,并且能够准确的预测强压力梯度区以及分离区内的流动平均统计特性.不考虑压力梯度效应的平衡层模型显著低估了壁面摩擦力的分布,同时无法准确预测分离区内的平均速度剖面.非平衡模型的修正项正比于切向压力梯度和壁面法向距离,因此在强压力梯度区或者网格较粗时,计算得到的平均压力和摩擦力分布以及流动的低阶统计量均与参考的实验和计算结果吻合.在此基础上,通过回转体绕流的大涡模拟考查了该方法用于模拟高雷诺数壁湍流的适用性,非平衡壁模型可以准确地捕捉流动的物理结构并较准确地预测其水动力学特性.结果表明,将浸入边界方法与非平衡滑移速度壁模型相结合的大涡模拟,有望成为数值模拟复杂边界高雷诺数壁湍流的工具.

Abstract: A slip-wall model is combined with the immersed boundary method for large-eddy simulation of flows with complex geometries. Firstly, large eddy simulation of flows over periodic hills are conducted to evaluate the effects of the tangential pressure gradient in wall model. Both the equilibrium stress balance model which based on the assumption of an equilibrium boundary-layer and the non-equilibrium wall model, in which the pressure gradient blend into the simplified thin boundary-layer equations and the RANS-like eddy viscosity in both the procedure of computing the wall-shear stress and reconstructing the wall-slip velocity, are utilized for comparison. The numerical results show that the pressure coefficient is not sensitive to the types of wall model which we considered, especially the strong pressure gradient in front of the hill crest is well catched by both models. However, when taking into account the tangential pressure gradient, the non-equilibrium wall model is superior to the equilibrium one for its ability to improve the prediction of the wall-shear stress and flow separation. When the equilibrium stress balance model is used, the wall-shear stress is heavily under-predicted and remarkable discrepancies of the mean velocity profiles can also be seen in the recirculation region. By comparison, the correction of the non-equilibrium wall model is proportional to both the tangential pressure gradient and the normal distance away from the wall, thus the hydrodynamic coefficients and the mean flow statistics are all in good agreement with the references even on very coarse grids. Secondly, large-eddy simulation of flow around an axisymmetric body is conducted to assess the applicability of current method when applied to high Reynolds number wall-bounded turbulent flows. The flow structures and the hydrodynamic characteristics are well predicted by the non-equilibrium wall model. This work confirms that the immersed boundary method in combination with the non-equilibrium slip-wall model is a possible and promising way to deal with turbulent flows which have complex geometries.

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