流向强迫振荡圆柱绕流的涡脱落模态分析

通过求解采用ALE方法描述的运动坐标系Navier-Stokes方程组，分析均匀来流下雷诺 数为150的静止和流向振荡的圆柱绕流. 主要研究了强迫振荡频率和较大振幅比 (A/D=0.3-1.2)对圆柱升力、阻力变化特性以及涡脱落模态的影响. 研究表 明，流向振荡圆柱绕流存在多种涡脱落模态，如对称S以及反对称A-I, A-III, A-IV等多种形式；比较研究结果，拓展了各模态下对应的锁定区域，并将其分为5个 子区；A-I模态中圆柱受力较以前所知更复杂；通过分析计算结果，发现最大加速度 比Af_{c}^{2}/Df_{s0}^{2}可能是涡脱落模态(尤其是对称S模态)最有效的控制参数.

ANALYSIS OF VORTEX SHEDDING MODES OF AN IN-LINE OSCILLATING CIRCULAR CYLINDER IN A UNIFORM FLOW

Flows around stationary and in-line oscillating circular cylinder in uniform flow at Reynolds number of 150 is studied by solving Navier-Stokes equations on a moving grid system which described by Arbitrary Largangian-Eulerian (ALE) method. The main objective is to investigate the lift and drag features and vortex shedding modes through different reduced oscillating frequencies and a little strong amplitudes, where the ratio of amplitude and diameter A/D is from 0.3 to 1.2. Present numerical results show that there are several modes of vortex shedding such as symmetrical S and anti-symmetrical A-I, A-III and A-IV modes. Through analysis of previous and present results, the region of lock-on is extended, which is divided into five sub-regions. Especially, the force on the circular cylinder at anti-symmetrical A-I mode shows more complex characters than the original mode. Based on the experimental and numerical results, we suggest that the radio of maximum acceleration Af_{c}^{2}/Df_{s0}^{2} should be an important parameter for vortex shedding modes, especially for the symmetrical S mode.