3D vortex formation of rigid and flexible plates in impulsively starting motion

TL;DR

This study experimentally investigates how flexibility influences 3D vortex formation and hydrodynamic forces in impulsively starting plates, revealing significant differences between rigid and flexible cases using advanced flow visualization.

Contribution

It provides new insights into the impact of plate flexibility on vortex dynamics and force generation during impulsive motion, using defocusing digital particle image velocimetry.

Findings

Flexible plates produce different vortex morphologies than rigid plates.

Tip deflection causes the differences in vortex formation.

Flexible plates exhibit smoother force and vortex shedding trends.

Abstract

This fluid dynamics video shows three-dimensional vortex formation process for plates in impulsive motion which is investigated experimentally by using defocusing digital particle image velocimetry (DDPIV). Rigid and flexible plate cases are compared in order to study the effect of flexibility on 3D vortex formation and associated hydrodynamic forces. This study was motivated by the general question of how the flexibility of flapping propulsors in flying and swimming animals affects vortex formation and propulsive force. For translating and rotating motion, the flexible plate generates a vortex morphology which is drastically different from that of the rigid plate. We identified the deflection of the tip region as the source of this difference. The flexible plate does not produce a large peak for the hydrodynamic force at the impulsive start and stop. This force trend is correlated with smooth vortex formation and shedding processes.