On the Jets Induce by a Cavitation Bubble Near a Cylinder

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, there are currently no established criteria for classifying the onset and directions of jets created by cavitation near a curved cylinder surface. In this study, we propose models to predict the occurrence and directions of jets in such scenarios, based on the non-dimensional bubble stand-off distance and the cylinder diameter. Our models are validated by comprehensive experiments. The results not only provide insights into the jetting behaviour but serve as guidelines for the design and control of jets when a cavitation bubble collapses near a cylinder, whether for protective or destructive purposes.