层流条件下并列三圆柱涡激振动响应与尾流形态

应用基于嵌入式压强-力迭代的高精度浸入边界法研究等间距并列三圆柱涡激振动。其中,雷诺数Re=100,间距比T/D=2.0～5.0,圆柱质量比m*=2.0,折合流速Ur=2.0～10.0,忽略振动系统的阻尼且三圆柱仅横向振动。研究发现,圆柱的振动响应随折合流速的增加呈现初始响应分支和下端响应分支两种模式;振幅响应出现不连续现象,且随着间距比的增加,该不连续现象对应的折合流速增加;尾流模式与间距比和折合流速密切相关。共发现六种尾流形态,分别为窄宽窄尾流、不规律尾流、反相同步尾流、调制尾流、同相同步尾流和偏斜尾流。总结并绘制了尾流形态在参数空间Ur,T/D]内的分区图。

Flow-induced vibrations of three side-by-side cylinders in laminar flow: vibration response and near-wake patterns

Flow-induced vibrations (FIVs) of three side-by-side cylinders are numerically investigated using a highly accurate immersed boundary method (IBM) utilizing the built-in pressure-force iterations.The Reynolds nubmer is Re=100.The center-to-center spacing ratio T/D is set as 2.0,2.5,3.0,4.0,5.0,respectively.The mass ratio is m^*=2.0 and the reduced velocity is in the range of U_r=2.0~10.0,the damping ratio is zero.The vibration of the cylinders is allowed only in the cross-flow direction.It was found that the response of the cylinders experiences two vibration modes,i. e.the initial and the lower branches,with the increasing reduced velocity.A discontinuity is observed in the response.With the increase of spacing ratio,its corresponding reduced velocity increases.The near-wake patterns significantly depend on T/D and U_r.Six near-wake patterns are observed,i.e.,the narrow-wide-narrow pattern,the irregular pattern,the anti-phase-synchronized pattern,the modulated pattern,the in-phase-synchronized pattern and the biased gap-flow pattern.A partition map of the near-wake patterns in the parameter spaceU_r,T/D] is given.