高雷诺数下方柱绕流特性的数值模拟

为研究高雷诺数为22 000下方柱周围流场形态及气动力特性，基于开源计算流体动力学（computational fluid dynamic，CFD）软件OpenFoam平台，采用基于动态亚格子模型的大涡模拟（large eddy simulation，LES）方法，对均匀来流作用下的方柱绕流进行了三维数值模拟.首先，通过对基于时间积分的平均积分分量的比较，验证了本数值计算的准确性；其次，深入分析了方柱周围及其尾流区的流场结构，给出了流场结构的平均和湍流特征，并在此基础上，研究了其气动力特性；最后，分析了两种长径比下表面压力的展向空间相关性.研究结果表明:雷诺数为22 000下方柱尾流区回转长度为1.37倍方柱宽度，Strouhal数为0.121，脉动升力系数为1.40；展向长度取8倍方柱宽度可更准确地获得周围湍流特性. 

Numerical Study of Flow Characteristics Around Square Cylinder at High Reynolds Number

Three-dimensional large eddy simulations (LES) were performed at high Reynolds numbers (Re=22 000) and using the dynamic Smagorinsky sub-grid model to investigate uniform flow over a square cylinder. Meshing of the model was performed using Open Foam-an open-source computational tool. Mean integral quantities were compared against existing experimental and numerical results to validate the proposed numerical method. Subsequently, the flow structure around and aerodynamic forces acting on the cylinder were analysed to perform an in-depth investigation of mean-and turbulent-flow characteristics. Lastly, the influence of the grid system around the cylinder and span-wise length on the flow structure and spatial correlation were investigated via comparison between different cases. Results demonstrate that the recirculation length in the wake approximately measured 1.37D (width of square), while the Strouhal number and RMS value of the lift coefficient are 0.121 and 1.40, respectively. In addition, domain length along the span-wise should be equal to 8D in order to obtain clear turbulent-flow characteristics.