液体纵荡SPH法模拟中两种不同外激励加载方式的比较研究

THE COMPARISON OF TWO DIFFERENT LOAD METHODS OF EXTERNAL FORCE IN SIMULATING LIQUID SLOSHING BY SPH

液体纵荡是一种复杂的流体运动现象,自由液面的存在使得该现象具有很强的非线性和随机性。在基于SPH法的二维矩形容器内液体纵荡研究中,存在边壁加载和相对加速度加载两种不同的外激励加载方式。该文分别采用这两种加载方式,获得其在不同外激励振幅、不同外激励周期及不同水深下的计算结果,通过对容器内某一截面位置的液面波动曲线及其波动频谱图的分析,同时将上述结果与理论解作对比,探讨了在液体纵荡问题研究中这两种加载方式的异同。分析结果表明:在不同振幅外激励作用下,边壁加载方式较相对加速度加载方式所得结果更接近于理论解;当外激励周期与理论固有周期接近时,边壁加载方式和相对加速度加载方式所得结果比较一致;而当外激励周期与理论固有周期远离时,边壁加载方式所得结果更接近于理论解;在不同水深下,边壁加载和相对加速度加载方式下的计算结果均比较一致。

Liquid sloshing is a very complicated phenomenon, and the existence of free surface makes this phenomenon being of strong non-linearity and randomness. In the simulation of liquid sloshing in 2D rectangle flume by SPH, there are two different load methods of external force which include loading external force onto the brim of flume and loading relative acceleration onto water particles directly. The numerical results are obtained by using these two methods with different amplitudes, different periods of external forces and different depths of water. Based on the analysis of vibration curves of liquid surface and frequency charts, and according to the comparison between numerical results and theoretical results, the similarities and differences between these two methods are discussed. Analysis results show that, firstly, loading external force onto the brim of flume is better than loading relative acceleration onto water particles directly when only the amplitude of external force is changed; secondly, both methods can reach the same results if the period of external forces closes to theoretical period, and when the period of external forces away from theoretical period, the former is better; thirdly, according to the analysis of vibration curves of liquid surface and frequency charts, the numerical results obtained by both methods are comparatively identical if lust water depth is changed.