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本文采用有限体积法和VOF方法,对不同自由液面高度(Z=1D～4D,其中D为圆柱直径)下的圆柱绕流进行了数值研究.研究1×l04≤Re≤7×104范围内,自由液面高度对圆柱绕流流场动力学特性和尾迹旋涡形态的影响.结果表明:自由液面的存在会导致圆柱的阻力系数和升力系数较无自由液面时减小.当Re一定时,阻力系数随着Z的增大而减小,升力系数随着Z的增大而增大.Z=1D时,自由液面的波动和变形较大,圆柱后旋涡形成受到自由液面的扰动,无法完全形成即脱落.随着Z增大,圆柱边界层逐渐向下拉伸,自由液面对圆柱后旋涡形成的扰动作用减弱.当Z=4D时,圆柱后尾迹旋涡形态已经基本与无自由液面流场的一致,可以观察到标准的卡门涡街图像.“,”The characteristics of flow around a circular cylinder submerged in the water with free surface are investigated numerically by finite volume method.The volume of fluid method (VOF) is introduced into the iteration of calculation to capture the free surface.The numerical simulations are conducted in high Reynolds numbers range from 10000 to 70000 at different height of free surface (Z =1D ～ 4D,D is the diameter of the circular cylinder).The effect of the height of free surface on the vortex structures and the lift and drag characteristics are discussed in this paper.Results indicate that the drag and lift coefficients are smaller than the cases without free surface.With increasing height of free surface,the drag coefficient decreases slightly and the lift coefficient increases.Vortices can be successfully formed even at a small free surface height of Z=1D.In this case,large deformation of the free surface is observed.The vortices are shed before completely formulation due to the interaction of the free surface in the wake of the circular cylinder.With the height of free surface increasing,the interaction of the free surface on the vortex shedding after the cylinder reduces.When Z=4D,the vortex patterns are similar to the case without free surface,which is the classical Kármán vortex street.