中文摘要：

自从人们对层流的圆柱绕流现象有了系列研究及清楚的认识后,人们逐渐把目光投向湍流的圆柱绕流,但相关研究主要关注于模拟湍流方法的数值格式和精度问题,而忽略了对高雷诺下圆柱绕流流场本身的认识及规律的总结。基于开源代码Open FOAM的大涡模拟方法以连续方程和Navier-Stokes方程为控制方程,选用Smargorinsky模式为亚格子应力模型,采用有限体积法和一次预测两次修正的PISO算法,对Re=3 900时三维圆柱绕流问题进行了数值模拟研究,并着重分析了其尾流特征和性质。数值计算结果表明：大涡模拟方法可以模拟出细致的流场结构,该雷诺数下的圆柱绕流具有很强的三维及湍流效应,在圆柱后方约一倍直径的范围内存在回流区域,在靠近圆柱壁面的尾流区域的速度剖面呈＂U＂型,远离壁面的速度剖面呈＂V＂型。瞬时速度剖面始终围绕着时均速度的周围脉动,且距离圆柱越远瞬时速度场的脉动范围越大。

英文摘要：

After a series of studies of laminar flow around circular cylinders,clear understanding was gained. People then set their sights on turbulent flow problems. However,relevant research mainly focused on the scheme and precision of numerical simulation methods at high Reynolds numbers; less attention was paid to the understanding of turbulent flow around circular cylinders itself. The simulations were carried out using large eddy simulation（ LES） solver within the open source code Open FOAM. The Navier- Stokes equations were discretized by the Finite Volume Method; the Smargorinsky model was chosen as Sub-grid stress model; the PISO algorithm with two prediction steps and one correction step were used to deal with the coupling between velocity and pressure. This paper emphatically analyzes the wake features of the three-dimensional flow around a circular cylinder at Re = 3 900. The numerical results show that LES can simulate the detailed flow structures,which exhibit strong three dimensional effects and turbulence effects at the current Reynolds number. The main conclusions of this study are that there exists a recirculation region about one diameter after the cylinder. The mean velocity profile in the region close to the cylindrical wall shows ＂U＂shape,while the velocity profile far from the wall exhibits＂V＂shape. The instantaneous velocity,which fluctuates around the mean velocity,has a larger amplitude of fluctuation as the distance from the cylinder gets farther.