Session: 05-09: Fluid Structure Interaction

Paper Number: 132969

132969 - Computational Analysis of Foil-Fish Interactions in Low Reynolds Number Flow 

Schooling swimmers can benefit from vortex interaction to increase hydrodynamic performance. To examine the underlying mechanisms of how schooling fish exploit periodically occurring vortices shed from the front, we conducted two-dimensional computational simulations in which a fish model was placed behind a pitching-plunging foil. An in-house immersed-boundary method (IBM) based computational fluid dynamics (CFD) solver was used to solve the flow field and obtain the hydrodynamic performance regarding thrust generation and propulsive efficiency. The motion of the fish model was then calculated from the hydrodynamic pressure and shear on the fish. The simulation of foil-fish interaction enables the quantitative assessment of fish dynamics while revealing the formation of an unstable vortex structure. By manipulating the phase difference between the foil and fish motions, we anticipate observing shifts in the fish's stability state. In addition to studying single-fish setups, we introduced an extra fish into the vortex region to analyze multiple-fish dynamics and the resultant vortex structures. Results of thrust coefficient, power coefficient, flow field, and dynamics motion were provided side-by-side for the fish-only cases and fish-foil cases. Our findings illustrate that vortex interaction impacts hydrodynamic performance diversely, influencing various school formations. This work offers a unique approach to comprehending fish schools, promising valuable insights into the mechanism behind hydrodynamic enhancement.

Presenting Author: Alec Menzer University of Virginia