均匀平面剪切流作用下圆柱体的涡激振动

对二维平面均匀剪切流作用下，弹性支撑圆柱体在横向和流向运动的涡激振动进行了数值模拟．数值计算实现了雷诺数在[2000，5000]内，圆柱体在不同剪切率[0．01，0．05]条件下的涡激振动．圆柱体的横向振幅、运动轨迹、振动频率和升力系数及位移时历曲线的计算结果表明，对于不同的雷诺数，存在剪切率的“锁定区间”．雷诺数较小时，剪切率的锁定区间较小，随着雷诺数的增加，剪切率的锁定区间增大．在剪切率的锁定区间内，横向振幅增大，脱离剪切率锁定区问后，横向振幅迅速下降．计算结果发现圆柱体的运动轨迹可以完全不同于普遍认可的“8”形轨迹，在剪切率锁定区间内圆柱体运动轨迹似“小雨点”的外形，这是在平面横向剪切流条件下得到的圆柱体运动的新轨迹．

Vortex-induced vibration of a cylinder in uniform planar shear flow

A numerical simulation of an elastically supported cylinder in 2-D uniform planar shear flow was conducted.It simulated the vortex-induced vibrations of a cylinder with Reynolds numbers ranging from 2 000 to 5 000 and shear rates ranging from 0.01 to 0.05.Numerical results,including transverse amplitudes,motion trajectories,vibration frequencies,and displacements show that there exists a shear rate lock-in range with respect to various Reynolds numbers.The shear rate lock-in range is relatively narrow when the Reynolds number is small,but it soars rapidly as the Reynolds number increases.Transverse amplitude increases when shear rate falls into the lock-in range and decreases sharply when shear rate is out of lock-in range.It is also found that the vibrating trace of the cylinder in a uniform planar shear flow is completely different from the "8" shape which was commonly known.We find that this new vibrating trace resembles a raindrop within the shear rate lock-in range.