纵向受迫振荡圆柱绕流问题的数值模拟

用有限体积法对平行于均匀来流方向受迫振荡的圆柱绕流问题进行了二维数值模拟.雷诺数选取Re=200、855、4000等几种亚临界雷诺数情况.通过研究不同振幅和振动频率下的流场结构和一些重要流动参数如升阻力系数、Strouhal数等随Re数、KC数、Stokes数的变化关系,验证了实验中观察到的一定条件下发生的"频率锁定"现象,并将涡脱落方式划分为三种主要模态.文中引入网格速度,对常用的处理速度与压力耦合的SIMPLE算法作了适当的补充和修改,以适应随时间变化的网格坐标.

COMPUTATIONAL STUDY OF UNSTEADY VISCOUS FLOW AROUND AN IN-LINE OSCILLATING CIRCULAR CYLINDER IN A UNIFORM FLOW

A finite volume method is presented for the time dependentviscous incompressible flow around an in-line oscillating circular cylinder at Reynolds number of 200、855 and 4000.The N-S equations in finite volume form are solved on a moving grid system, based on a time dependent coordinate transformation.To investigate the vortex-shedding characteristics behind the circular cylinder and the effects of Reynolds number and other non-dimensional parameters such as reduced amplitude and reduced frequency,several numerical schemes have been tested with different amplitudes and frequencies at each Reynolds number.Present numerical results indicate that several types of vortex shedding modes are mainly dependent on the reduced frequency and also the reduced amplitued,which is called synchronization or lock-on.