Research On Hydrodynamic Performance Of Shark Wagging

In the study of fish swimming mechanism,the crescent-shaped tail advancement,undulatory fin movement and swimming mechanism of swinging pectoral fins are considered to have the most development potential in artificial systems.This paper uses a combination of water tunnel experiments and numerical simulations to study the dynamic characteristics of sharks under different tail swing conditions to explore the propulsive ability of sharks.(1)In order to study the dynamic characteristics of shark tail wagging,based on the real shark shape,this article designs and sets up an experimental platform to study the dynamic characteristics of shark tail wagging,which can measure the hydrodynamics of shark tail wagging in real time,as well as detailedly introducing the system of the experimental bench.(2)This paper introduces the water tunnel test method and experimental data processing method of the 3D shark model in detail,and analyzes the dynamic characteristics of the shark tails obtained from the experiments,and studies the dynamic characteristics of shark tail wagging.When the shark tail swings,each tail swing frequency will correspond to an optimal maximum tail swing amplitude?_max,so that the shark tail swinging efficiency is the highest.(3)Based on experimental research,numerical simulation methods are used to analyze the hydrodynamic parameter characteristics of the shark model at different tail swing frequencies,different tail swing angles,and different Reynolds numbers.Also analyze the different methods to achieve the same steady-state swimming situation,as well as propulsion efficiency.At the same time,specific analysis of the flow field characteristics under different operating conditions was conducted to explore the effect of the wake on the fish swimming when the shark swung its tail.Sharks can reach the same cruising status by changing a single variable(f,?_max);when sharks reach the same cruising point in different swimming modes,the small frequency and large swing tail angle method is more labor-saving,because of the lower energy.(4)Finally,the experimental results of the shark tail wagging experiment and the CFD calculation results are compared and analyzed.The hydrodynamic test of the shark tail swing and the CFD numerical simulation results are pretty reliable.