Marching of Freely Falling Plates

TL;DR

This paper presents direct numerical simulations of freely falling plates to explore their complex fluid-structure interactions, including transitions between fluttering and tumbling, and aims to better understand vortex dynamics and aerodynamic forces.

Contribution

It provides detailed DNS results of freely falling plates, linking plate motion, vortex formation, and aerodynamic forces, advancing understanding of their fluid dynamics behavior.

Findings

Identification of transition regimes between fluttering and tumbling.

Analysis of vortex generation related to plate rotation.

Insights into fluid-structure interaction in multi-body systems.

Abstract

"Marching of freely falling plates" is a fluid dynamics video for the Gallery of Fluid Motion submitted to APS-DFD 2011 at Baltimore Maryland. The problem of a freely falling plate is of interest in both fluid mechanics and nonlinear dynamics. The trajectory of the plate can be regular (Willmarth et al., 1964) or chaotic (Aref and Jones, 1993). As long as Reynolds number is high enough, regular flutter and tumble motion can be obtained for plates with small and large Froude numbers respectively. Belmonte et al. (1998) conducted experimental study on thin flat strips falling in a vertical cell. They categorized the Froude number at which the transition from fluttering to tumbling occurs. Andersen et al. (2005) analyzed the transitions between fluttering and tumbling using vorticity-stream function formulation and ODE dynamic equations based on quasi-steady models. They also found that the fluid circulation is mainly generated by the plate rotation and its angular velocity. However, the correlation among the plate motion, generated vortices, and aerodynamic forces is still not fully understood yet, especially in the case of multiple bodies. The DNS (Direct Numerical Simulation, Dong et al., 2006) of freely falling plates is conducted using our in-house CFD (Computational Fluid Dynamics) solver. Showcased examples in this video are a part of DNS results in the attempt to answer the above question.