中文摘要：

采用三步有限元方法直接求解ALE描述的N—S方程组，结合ALE动网格技术，建立了2D横向受迫振动的数值模型。利用该模型计算了1个主圆柱体与4个附属小圆柱体的横向受迫振动问题，Re=185，振幅比Ae／D=0．2，频率比fe／fs=0．86～1．04，间隔0．01。通过分析总流体力及其频谱随频率比的变化，发现总流体力出现了突变，且流体力的振动模态可以分为4种不同的类型，其中包括基本锁定状态。最后分析了升力突变前后流体-结构能量传递关系、结构位移和升力的相位关系以及涡脱落模式的变化。

英文摘要：

Three steps finite element method is used to directly solve the N-S equations described by ALE method, and combining with ALE dynamic grid technique, a numerical model for 2D lateral forced vibration is developed. The lateral forced vibration of one main circular cylinder with additional four smaller circular cylinders is calculated, at Re=185, amplitude ratioAe/D =0.2 and frequency ratio fe/fs =0.86-1.04 with interval of 0.01. By analyzing the total fluid forces and their spectrums as a function of fe/fs, an abrupt change on total lift force is found, and the oscillating mode of fluid force can be divided into four types including the primary lock-in regime. Then the fluid-structure energy transfer, the phase between structural movement and lift force and the vortex shedding mode are analyzed to realize the nature on account for abrupt change of fluid force.