多个淹没水平圆柱诱发高阶谐波特性的数值与试验研究

Numerical and experimental investigations on higher harmonics induced by multiple horizontal cylinders

基于势流理论采用时域高阶边界元方法建立了模拟非线性波浪与淹没水平双、三圆柱作用的数值水槽模型,其中采用混合欧拉-拉格朗日方法更新自由水面,四阶Runga-Kutta方法进行时间步进。利用两点法分离得到潜体下游高阶自由波,进而研究潜体间距、布置形式等对高倍频自由波的影响。同时在物理水槽内开展多潜体高阶谐波物理模型试验,并将试验结果与数值结果进行对比,吻合较好。研究发现:淹没双圆柱下游高阶谐波幅值随潜体间距呈现周期性振荡变化,其振荡的重现距离约为波长一半。而淹没三圆柱下游的高阶谐波随第一个间距呈周期性振荡变化,随第二个间距的增大而减小。

Based on potential flow theory,a numerical wave flume was founded to model the interaction of nonlinear waves and dual or triple submerged horizontal cylinders by using a time-domain higher-order boundary element method.The mixed Eulerian-Lagrangian technique was used for the refresh of free surface,and the 4th-order Runga-Kutta scheme was adopted for the time advance.The two-point method was adopted to separate the higher free harmonics from the downstream waves.Then the effects of interval of submerged objects and distribution scheme on the higher free harmonics were investigated.Meanwhile,physical tests were carried out for higher harmonics induced by multiple submerged objects in a wave flume.Good agreements between the numerical results and experimental data were obtained.It was found that higher free harmonic amplitude oscillates periodically with the variation of the interval in the dual cylinder system.And the reoccurrence interval is near to half wave length.In the triple cylinder system,higher free harmonics amplitude oscillates periodically with the first interval but decreases with the second interval.