Research on the coupled impact dynamics characteristics of cavitation bubble-particle groups near a flat wall surface

The synergistic interaction between cavitation bubbles and particles is an important frontier in multiphase flows, closely related to structural damage mitigation and applications such as ultrasonic medical treatment. In engineering practice, particles typically exist as particle groups, and studies based on a single cavitation bubble and a single particle cannot capture collective effects or the interference of multiple cavitation bubbles on wall impacts. Therefore, the basic configuration considered consists of different numbers of linearly aligned cavitation bubbles near a flat wall. By combining visualization experiments, Kelvin impulse analysis, and numerical simulations, momentum redistribution, jet evolution, and wall impact risk are elucidated. The results indicate that particle group wall impact is governed by dimensionless distance and configuration parameters. The wall impact effect is strongest when the dimensionless bubble wall distance for a single cavitation bubble is close to 1.4. For double cavitation bubble, varying the inter bubble parameter reconstructs the jet and particle response and significantly reduces particle wall impact risk when the dimensionless distance from cavitation bubble 1 to the wall is close to 2. For three cavitation bubble, the coupling strength is dominated by the relative inter bubble spacing, and the wall impact effect is strongest when this ratio exceeds 1. An impact risk criterion based on the fraction of normal energy is proposed, and a Kelvin impulse based correlation between cavitation bubble impulse and particle wall impact is established, providing a basis for predicting and controlling the coupled impact dynamics of multiple bubbles and particle groups.