双鱼集群水动力和游动性能研究

RESEARCH ON HYDRODYNAMIC AND SWIMMING PERFORMANCE OF TWO-FISH SWIMMING

为探索鱼类在群聚游动中水动力相互作用以及游动性能的影响,采用基于虚拟单元的锐利界面浸没边界法对双鱼以不同横向间距、纵向间距和尾摆相位差游动的问题进行了数值研究,并对双鱼的水动力性能和流场进行了综合分析。研究结果表明,在适当的位置和相应的尾摆相位差下,跟随鱼的游动性能可以得到显著的提高,同时影响领头鱼的游动性能。本文建议横向间距的最佳选择不应小于0.3倍体长。此外,通过考虑流场压力来探究双鱼间的水动力相互作用机制,发现双鱼间推力的产生同时受贴体压力和尾流动力的影响。分析表明,这两种影响的主导地位会随着双鱼间的位置变化而改变,当流向间距小于0.4倍的体长时,由贴体压力主导,当流向间距大于0.4倍的体长时,则改为由尾流动力所主导。这项研究可以为生物的集群游动力学机理提供一些见解,并支撑仿生潜航器的研制。

The motivation of this research is to explore the hydrodynamic interactions and swimming performance of fish school swimming.The paper used a sharp interface immersed boundary method based on virtual cells to numerically investigate the swimming of two fish with different lateral and longitudinal distances and phase differences of tail beats.The hydrodynamic performance and flow fields of the two fish were comprehensively analyzed.The research results indicate that,under appropriate positions and corresponding tailbeat phase differences,the trailing fish can significantly enhance its swimming performance,while also affecting the leading fish's swimming performance.This article suggests that the optimal choice for lateral spacing should not be less than 0.3 time of the body length.In addition,by considering the pressure in the flow field,the hydrodynamic interaction mechanism between the two fishes is understood.It is found that the generation of thrust between the two fishes is simultaneously influenced by both the body pressure and the wake-induced forces.Analysis shows that the dominance of these two influences will change with the position between the two fishes.When the streamwise distance is less than 0.4 time of the body length,it is dominated by the body pressure.When the streamwise distance is greater than 0.4 time of the body length,it switches to being dominated by the wake-induced forces.This study provides insights for the understanding of the collective swimming behavior and supports the development of biomimetic underwater vehicles.