Numerical Study of Flow Past a Wall-Mounted Dolphin Dorsal Fin at Low Reynolds Numbers

TL;DR

This study uses high-accuracy 3D simulations to analyze flow around a wall-mounted dolphin dorsal fin at low Reynolds numbers, revealing vortex formation and lift/drag behavior relevant for underwater vehicle design.

Contribution

It provides detailed numerical analysis of flow dynamics around a dolphin dorsal fin at low Reynolds numbers, which is underexplored in current research.

Findings

Drag and lift increase with angle of attack.

Vortex structures emerge at angles ≥30°.

Flow behavior insights for underwater robot design.

Abstract

Dolphin swimming has been a captivating area of study, yet the hydrodynamics of the dorsal fin remain underexplored. In this study, we present three-dimensional simulations of flow around a wall-mounted dolphin dorsal fin, derived from a real dolphin scan. The NEK5000 (spectral element method) is employed with a second-order hex20 mesh to ensure high accuracy and computational efficiency in the simulations. A total of 13 cases were simulated, covering angles of attack (AoA) ranging from $0^\circ$ to $60^\circ$ and Reynolds numbers ($\text{Re}$) between 691 and 2000. Our results show that both drag and lift increase significantly with the AoA. Almost no vortex is observed at $\text{AoA} = 0^\circ$, whereas complex vortex structures emerge for $\text{AoA} \geq 30^\circ$, including half-horseshoe, hairpin, arch, and wake vortices. This study offers insights that could inform the design of next-generation underwater robots, heat exchangers, and submarine sails.