Cheng J Y, Chahine G L
Dynaflow Inc., 10621-J Iron Bridge Rd., Jessup, MD 20794, USA.
Comp Biochem Physiol A Mol Integr Physiol. 2001 Dec;131(1):51-60. doi: 10.1016/s1095-6433(01)00464-0.
The slender body theory, lifting surface theories, and more recently panel methods and Navier-Stokes solvers have been used to study the hydrodynamics of fish swimming. This paper presents progress on swimming hydrodynamics using a boundary integral equation method (or boundary element method) based on potential flow model. The unsteady three-dimensional BEM code 3DynaFS that we developed and used is able to model realistic body geometries, arbitrary movements, and resulting wake evolution. Pressure distribution over the body surface, vorticity in the wake, and the velocity field around the body can be computed. The structure and dynamic behavior of the vortex wakes generated by the swimming body are responsible for the underlying fluid dynamic mechanisms to realize the high-efficiency propulsion and high-agility maneuvering. Three-dimensional vortex wake structures are not well known, although two-dimensional structures termed 'reverse Karman Vortex Street' have been observed and studied. In this paper, simulations about a swimming saithe (Pollachius virens) using our BEM code have demonstrated that undulatory swimming reduces three-dimensional effects due to substantially weakened tail tip vortex, resulting in a reverse Karman Vortex Street as the major flow pattern in the three-dimensional wake of an undulating swimming fish.
细长体理论、升力面理论，以及最近的面元法和纳维-斯托克斯求解器都已被用于研究鱼类游动的流体动力学。本文介绍了基于势流模型，使用边界积分方程法（或边界元法）在游动流体动力学方面取得的进展。我们开发并使用的非定常三维边界元程序3DynaFS能够对实际的身体几何形状、任意运动以及由此产生的尾流演变进行建模。可以计算身体表面的压力分布、尾流中的涡度以及身体周围的速度场。由游动身体产生的涡尾流的结构和动态行为是实现高效推进和高敏捷机动性的潜在流体动力学机制的原因。尽管已经观察和研究了被称为“反向卡门涡街”的二维结构，但三维涡尾流结构却并不为人所熟知。在本文中，使用我们的边界元程序对一条游动的绿青鳕（Pollachius virens）进行的模拟表明，波动式游动由于尾尖涡大大减弱而减少了三维效应，从而在波动式游动鱼类的三维尾流中形成了以反向卡门涡街为主要流动模式的情况。
