中文摘要：

数值研究了直径变化对三圆柱绕流的影响。在上游布置一个直径在d/D 0.15~2.0范围变化的圆柱,再以并列形式布置两个直径为D的圆柱。用有限元法对不等直径三圆柱的二维绕流进行数值模拟,分别求出在不同直径比下的流场分布和各个圆柱的升、阻力系数以及Strouhal数。结果发现：在直径比的变化过程中,流场可分为五类;升、阻力系数和Strouhal数的变化都有一定规律。

英文摘要：

The wake of flow of three cylinders with different diameters has been investigated by numerical simulation method.Two cylinders with the diameter of D are placed side-by-side after a front cylinder with diameter ratio range of d/D = 0.15～2.0.Finite Element Method is applied to simulate the 2D flow problem and flow field distribution,coefficients of the lift and drag,and Strouhal number are obtained.The results indicate that as the change of the diameter,the flow field can be divided into five categories,and coefficients of forces and Strouhal numbers also have some regular variation pattern.