On the Jets Induced by a Cavitation Bubble Near a Cylinder

TL;DR

This paper develops models to predict when and in which direction cavitation bubbles near cylinders will produce jets, validated by experiments, with applications in water treatment, biomedical engineering, and material cleaning.

Contribution

The study introduces new predictive models for cavitation bubble jetting behavior near cylinders, based on stand-off distance and cylinder size, validated through experiments.

Findings

Models accurately predict jet occurrence and direction.

Jet behavior depends on bubble stand-off and cylinder diameter.

Results aid in designing cavitation-based processes.

Abstract

The dynamics of cavitation bubbles in the vicinity of a solid cylinder or fibre are seen in water treatment, demolition and/or cleaning of composite materials, as well as bio-medical scenarios such as ultrasound-induced bubbles near the tubular structures in the body. When the bubble collapses near the surface, violent fluid jets may be generated. Understanding whether these jets occur and predicting their directions -- departing or approaching the solid surface -- is crucial for assessing their potential impact on the solid phase. However, the criteria for classifying the onset and directions of the jets created by cavitation near a curved surface of a cylinder have not been established. In this research, we present models to predict the occurrence and directions of the jet in such scenarios. The onset criteria and the direction(s) of the jets are dictated by the bubble stand-off distance and the cylinder diameter. Our models are validated by comprehensive experiments. The results not only predict the jetting behaviour but can serve as guidelines for designing and controlling the jets when a cavitation bubble collapses near a cylinder, whether for protective or destructive purposes.