基于动态亚格子模型的方柱绕流大涡模拟

Large Eddy Simulation of Flow Past a Square Cylinder Based on Dynamic Sub-Grid Scale Models

目的对高雷诺数下的方柱绕流进行数值模拟,得到方柱下流场时间平均结果以及湍流流场的流场特征,用于验证亚格子模型对大涡模拟(LES)计算精确性的影响.方法基于有限体积法(FVM)的流体计算开源软件OpenFOAM,采用两种不同动态亚格子模型下的大涡模拟方法,模拟高雷诺数(Re=2.2×104)下的方柱绕流.结果通过数值计算得到流场完整的平均和脉动结构,并得到阻力系数、升力系数、斯托拉哈数等重要的气动力参数,经对比与试验实际情况吻合.结论高雷诺数复杂流场下亚格子应力的封闭形式对大涡模拟的计算结果有重要的影响,采用动态模拟技术一方程模型计算结果优于常规的Smagorinsky模型,在高雷诺数复杂流场下的计算是高效的,为结构抗风的数值研究提供了参考.

Flow past a bluff body under high Reynolds number always contains big scale flow separation and recirculation, thus is more complex than low Reynolds number flows and hard to be simulated. This paper concerns the presentation of the sub-grid scale models in the large eddy simulation（LES） ,which is consid- ered to be a better choice under this situation. Besides that, the characteristics of the three dimensional turbu- lent flows are also specifically analyzed. The simulations are carded out using the open source fluid computa- tional software OpenFOAM, which are designed based on finite volume method（FVM）. Two different dy- namic sub-grid scale models which are dynamic Smagorinsky model and dynamic one-equation model are employed, and the results are compared with the past experimental and simulation results. Meanwhile, the mean flow and turbulence characteristics and the wake structures are performed. The result proves the impor- tance of the proper construction of the sub-grid scale stress, and the dynamic one-equation model is qualified to be a better choice than generally used dynamic Smagorinsky model under high Reynolds number turbu- lence simulation. The application of LES method combined with high precise dynamic sub-grid scale model should be paid more attention in wind engineering numerical simulation.