Larger wavelengths suit the hydrodynamics of carangiform swimmers

TL;DR

This study uses numerical simulations to show that larger undulatory wavelengths enhance the hydrodynamic efficiency of carangiform fish by improving thrust, reducing drag, and lowering power consumption, with real fish kinematics outperforming prescribed models.

Contribution

It provides a detailed numerical analysis demonstrating how larger wavelengths improve hydrodynamic performance in carangiform swimmers, incorporating real fish kinematics.

Findings

Larger wavelengths increase thrust and reduce drag.

Real fish kinematics outperform prescribed motion models.

Stronger vortices form with larger wavelengths, enhancing efficiency.

Abstract

The wavelength of undulatory kinematics of fish is an important parameter to determine their hydrodynamic performance. This study focuses on numerical examination of this feature by reconstructing the real physiological model and kinematics of steadily swimmning Jack Fish. We perform three-dimensional numerical simulations for flows over these models composed of the trunk, and dorsal, anal, and caudal fins. Moreover, we prescribe the carangiform-like motion for its undulation for a range of wavelengths. Undulation with larger wavelengths improves the hydrodynamic performance of the carangiform swimmer in terms of better thrust production by the caudal fin, lower drag production on the trunk, and reduced power consumption by the trunk. This coincides with the formation of stronger posterior body vortices and leading-edge vortices with more circulation on the caudal fin. The real kinematics of Jack Fish surpasses the performance of those with prescribed motion owing to the flexibility of the caudal fin.