Numerical investigation of bubble dynamics at a corner

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Colleges, School and Institutes

Abstract

This paper is concerned with bubble dynamics at a corner formed by two flat rigid boundaries associated with applications in ultrasonic cleaning and cavitation damage. This phenomenon is modeled using the potential flow theory and the boundary integral method. The Green’s function is obtained to satisfy the impenetrable conditions at the rigid boundaries using the method of images with the corner angle α = π/k, where k is a natural number. To evaluate the numerical model, experiments were carried out with a spark-generated bubble in water and recorded using a high-speed camera. The predicted bubble shapes are in excellent agreement with those from the experiments. A jet forms toward the end of the collapse, pointing to the corner when initiated at the bisector of the two walls but pointing to the near wall and inclined to the corner when initiated near one of the two walls. The Kelvin impulse theory predicts the jet direction well. As compared to a bubble near a flat wall, the oscillation period and the jet width increase but the jet velocity decreases. The bubble migrates away from the near wall and the corner during its expansion and moves back toward them during its collapse, but at a much larger speed and amplitude. A velocity stagnation point forms at the start of the collapse, and a high-pressure zone is generated at the base of the jet during the late stages of the collapse, which drives the jet and the bubble toward the near wall and the corner.

Details

Original languageEnglish
Article number053306
JournalPhysics of Fluids
Volume32
Publication statusPublished - 8 May 2020