Numerical simulation of vortex-induced drag of elastic swimmer models

TL;DR

This paper uses numerical simulations to study how vortex effects influence the drag and cruising velocity of elastic swimmer models with different shapes, highlighting the importance of tip vortices in propulsion efficiency.

Contribution

It introduces a numerical approach to analyze the impact of three-dimensional tip vortices on the swimming performance of elastic plates with various aspect ratios and shapes.

Findings

Contracting shapes achieve higher cruising velocities.

Tip vortices significantly affect drag and velocity.

Shape and aspect ratio influence vortex interactions and performance.

Abstract

We present numerical simulations of simplified models for swimming organisms or robots, using chordwise flexible elastic plates. We focus on the tip vortices originating from three-dimensional effects due to the finite span of the plate. These effects play an important role when predicting the swimmer's cruising velocity, since they contribute significantly to the drag force. First we simulate swimmers with rectangular plates of different aspect ratio and compare the results with a recent experimental study. Then we consider plates with expanding and contracting shapes. We find the cruising velocity of the contracting swimmer to be higher than the rectangular one, which in turn is higher than the expanding one. We provide some evidence that this result is due to the tip vortices interacting differently with the swimmer.