Reynolds Number Effect on the Leading-Edge Vortex Induced by Fish-Like Lambari Swimming

Abstract

Traditionally, the literature about fish swimming focuses on investigating the fish trailing wake. However, recently, Borazjani and Daghooghi [1] reported that studying the leadingedge vortex generated during fish swimming is a crucial issue in biomechanics analysis, in the same direction that similar works about the flight of insects and birds. Thus, we investigate the leading-edge vortex induced by a fish-like lambari (Astyanax bimaculatus) swimming in a three-dimensional viscous flow and the force productions at different Reynolds and Strouhal number. Numerical simulations are carried out employing the URANS approach with turbulence closure model transition k-?-SST and a deformable mesh condition to the fish swimming. It is observed that the leading-edge vortex attached to the caudal fin increases the propulsive force at equilibrium configurations (thrust and drag balanced). Besides, at lower Reynolds numbers, it is noted that the vortex, once detached, travels more slowly in the wake, locating closer to the caudal fin due to the delay of fluid convection.