金枪鱼自主波动游动的数值模拟

Numerical simulation of tuna undulatory swimming

鱼类游动问题蕴含着复杂的流体力学机理,其仿生问题同时又有着重要应用背景。该文运用人工伪压缩方法求解三维不可压缩非定常Navier-Stokes方程,计算分析金枪鱼从静止加速起动到巡游直至减速波动游动的全过程,得到鱼类游动时各状态的流场信息以及受力情况。同时结合计算结果,对鱼类游动过程进行了参数研究并且分析了鱼体推力产生的机理。计算结果分析表明:数值求解非定常Navier-Stokes方程能够模拟鱼体运动时的流场;鱼体摆动频率以及摆幅会影响鱼的游动;持续摆动产生的涡环形成反卡门涡街是鱼体游动时产生推力的重要因素。

The fish swimming is a complex hydrodynamic problem.It contains profound hydrodynamic mechanism and potential application.The tuna undulatory swimming was numerically simulated in this paper.The 3D incompressible Navier-Stokes Equation was solved using the artificial compressibility method.The flow field information around swimming fish and force distribution were obtained through the calculations.With these results,the parametric research and the propelling mechanism were analyzed.It was shown from the results that unsteady Navier-Stokes Equations is able to simulate correctly the flow fields of fish undulatory swimming;the reduced frequency and oscillation amplitude of the fish body can effect on the fish swimming;the reverse Karman vortex street arising from the continuing dissipative vortex ring is the main mechanism of the producing of thrust.