特征线算子分裂有限元的圆柱绕流大涡模拟

Large eddy simulation of flow around circular cylinder combined with characteristic-based operator-splitting finite element method

为研究圆柱绕流流场特性,将大涡模拟与特征线算子分裂有限元相结合,建立了大涡模拟特征线算子分裂有限元模型,对单圆柱和串列双圆柱绕流问题进行了数值模拟,所得结果与现有研究结果吻合较好。模拟结果表明:对单圆柱绕流,随着雷诺数的增大,圆柱近尾流区上下交替的涡旋逐渐靠近通过圆柱几何中心的水平线,且涡脱落位置逐渐靠近圆柱。对Re=1 000的串列双圆柱绕流,临界间距在圆柱直径的2.25~2.5倍之间;当两圆柱间距小于临界间距时,上游圆柱后方无明显涡旋脱落,间隙处压力较稳定;大于临界间距时,有涡旋脱落,上游圆柱尾流区上下表面交替出现强负压区。

In order to investigate the characteristics of flow fields around circular cylinders, a numerical model was developed by combing large eddy simulation （ LES） with the characteristic-based operator-splitting finite element method. The model was used to simulate flow fields around a circular cylinder and two circular cylinders in tandem arrangement, and the obtained results agree with the existing results. The simulation results show that, for the flow around a circular cylinder, with the increase of the Reynolds number, the vortexes occurring at the top and bottom surfaces alternatively in the near-wake region gradually approach each other and pass along the horizontal line through the geometric center of the cylinder, and the location of vortex shedding gradually approach the cylinder; for the two circular cylinders in tandem arrangement, with Re =1000,the critical space between the two circular cylinders is 2. 25 to 2. 50 times their diameters ; when the space between the two circular cylinders is smaller than the critical space, vortex shedding does not occur at the rear of the upstream cylinder,and the pressure in the space between the two circular cylinders is stable; when the space between the two circular cylinders is larger than the critical space, vortex shedding occurs, and strong negative pressure regions occur at the top and bottom surfaces alternatively in the near-wake region of the upstream cylinder.