Dynamics of a Bubble Cloud near a Rigid Wall

J Ma,C-T Hsiao,G L Chahine

doi:10.1088/1742-6596/656/1/012153

Abstract

Simulations involving a large number of interacting bubbles in a bubble cloud are conducted to assess the effect of frequency and amplitude of a sinusoidal driving pressure on the bubble cloud behavior. As the pressure amplitude increases strong nonlinear bubble dynamics become more pronounced and higher pressures are generated at the wall. A resonance frequency, corresponding to the highest collective bubble behavior, results in a pressure peak orders of magnitudes higher than the excitation pressure. This frequency is significantly different from the natural frequency of a spherical cloud executing small amplitude oscillations.

Highlights

The collapse of a cloud of bubbles near a rigid boundary is known to be one of the most destructive forms of cavitation
Using a generalized 3D two-way coupled Eulerian-Lagrangian model [3,4], this paper investigates the dynamics of a bubble cloud excited by a surrounding sinusoidal pressure field and computes the resulting pressures on a nearby rigid wall
When the driving pressure frequency matches the characteristic frequency of the bubble cloud, strong collective behavior occurs and very high pressures are generated at the wall

Summary

Introduction

The collapse of a cloud of bubbles near a rigid boundary is known to be one of the most destructive forms of cavitation It occurs in a variety of engineering applications including cavitation on propellers, ultrasonic cavitation, cavitating jets, Shock Wave Lithotripsy (SWL),.. All the models capture the average low-frequency dynamics, the microscale response of the discrete bubbles and the resultant high-frequency local fluctuations are only captured appropriately by the Eulerian-Lagrangian approach. This highlights that discrete bubble modeling is essential to a better understanding of the dynamics since it can resolve the physics down to the single bubble scale, while maintaining computation cost affordable to capture the overall large scale flow behavior. Using a generalized 3D two-way coupled Eulerian-Lagrangian model [3,4], this paper investigates the dynamics of a bubble cloud excited by a surrounding sinusoidal pressure field and computes the resulting pressures on a nearby rigid wall

Numerical Method

Driving Pressure Amplitude Effect of a bubble cloud near a

This is made further clear in

Driving Frequency Effects

Conclusions