Stability prediction of vortex induced vibrations of multiple freely oscillating bodies

TL;DR

This paper develops a new linear fluid-structure interaction method and an impedance-based criterion to predict vortex-induced vibrations and stability thresholds of multiple oscillating bodies, validated through experiments and parametric studies.

Contribution

It introduces a low-cost impedance-based stability prediction method for multiple bodies, validated with a new L-ALE approach and extended to three-body systems.

Findings

Impedance-based criterion accurately predicts instability thresholds.

The method is validated for tandem and three-body configurations.

Parametric study reveals effects of mass, damping, and spacing.

Abstract

The vortex-induced vibration of multiple spring-mounted bodies free to move in the orthogonal direction of the flow is investigated. In a first step, we derive a Linear Arbitrary Lagrangian Eulerian (L-ALE) method to solve the fluid-structure linear problem as well as a forced problem where a harmonic motion of the bodies is imposed. We then propose a low computational-cost impedance-based criterion to predict the instability thresholds. A global stability analysis of the fluid-structure system is then performed for a tandem of cylinders and the instability thresholds obtained are found to be in perfect agreement with the predictions of the impedance-based criterion. An extensive parametric study is then performed for a tandem of cylinders and the effects of mass, damping and spacing between the bodies are investigated. Finally we also apply the impedance-based method to a three-body system to show its validity to a higher number of bodies.