周期性变形圆柱绕流特征的数值分析

应用有限体积法求解不可压缩二维N-S方程，对在均匀来流中圆柱-椭圆柱周期性变形运动进行了数值模拟。对于两种典型状态，即雷诺数为40和100，本文描述了圆柱变形运动所引发的非定常流动随时间变化的过程，揭示了变形过程中柱体附近流场的变化主要取决于由壁面压力梯度和壁面的切向运动加速度所产生的壁面涡量流，分析了不同变形频率和不同变形量对升力和阻力、旋涡形成及其运动的影响，并发现了频率锁定现象。

Numerical simulation of periodically deforming circular cylinder

The characteristics of the flow behind a circular cylinder performing periodic deformation in a uniform flow are investigated. The two-dimensional incompressible Navier-Stokes equations are solved numerically to determine the flow field structure. Patterns of vortex shedding and force-coefficient curves are shown for Reynolds number of 40 or 100 and for different values of deforming amplitudes and deforming frequencies. The obtained results show that the controlling factor of the flow pattern near the periodically deforming cylinder is the vorticity flux on the solid wall, which is determined by the pressure gradient and the tangential acceleration on the solid wall. The lock-on phenomenon has been observed when Reynolds number is 100.