方柱绕流CFX三维数值模拟

Three dimensional numerical simulation of flow past a square cylinder using CFX

该文利用计算流体力学软件CFX,对恒定来流条件下黏性不可压缩流体的圆柱和方柱绕流进行了数值模拟。采用有限体积法和SIMPLE计算方法,求解不可压缩Navier-Stokes方程。首先开展雷诺数(Re)等于100和300时的圆柱和方柱绕流问题的二维数值模拟,分析比较了网格大小和时间步长对模拟结果的影响,并比较了不同柱体情况下的流体流动的差异性。进而对Re=100、300时方柱绕流问题进行了三维数值模拟,重点分析了各截面上阻力和升力系数、Strouhal数以及涡量特性与二维结果的差异。发现Re=300时,周向压力、速度场和涡量场与Re=100时相比存在明显的三维特性,并且由于二维流动结构发展成三维流动结构时需要消耗能量,导致三维的阻力升力系数计算结果均小于二维计算结果。研究表明,该文的数值结果与文献结果吻合良好。

Numerical simulation of a uniform viscous and incompressible flow past a circular cylinder and square cylinder was performed using computational fluid dynamics software CFX. The finite volume method and SIMPLE method for incompressible Navier-Stokes equations were employed in the model. Firstly, two dimensional flow past a circular cylinder and square cylinder was simulated at Re=100 and 300, with considerable attentions paid to the effect of the grid size on the results. The difference of the flow structure was also pointed out when the flow passed a circular cylinder and square cylinder. Secondly, three dimensional flow past a square cylinder was performed at Re=100 and 300. Main attentions were paid to the lift coefficient lC , drag coefficient dC and Strouhal number. Comparison between the three-dimensional result and the two-dimensional result indicates that the flow structure of different sections appears strong three-dimensional characteristics at Re=300. Compared with the results at Re=100, obvious three-dimensional characters can be observed at Re=300, such as pressure distribution, velocity and vorticity field. The results of three-dimensional simulation are smaller than that of two-dimensional because of energy consumption. Good agreement between the computations with available data validates that present study provides a good foundation for the further study of flow around cylinder and vortex-induced vibration problems.