How do bubbles collapse and displace near porous plates?

The collapse of a gas or vapour bubble near a solid boundary produces a jet directed towards the boundary. High surface pressure and shear stress induced by this jet can damage, or clean, the surface. A porous boundary, such as a filter, would act similarly to a solid boundary but with reduced effect. Prior research has measured the cleaning effect of bubbles on filters using ultrasonic cleaning, but how the bubble dynamics are fundamentally affected by the porosity of the surface is not known. We address this question experimentally by investigating how both the porosity and pore size of the boundary affects two collapse parameters: bubble displacement and bubble rebound strength. We measure these parameters for various porosity values, pore sizes, hole shapes, plate materials, and bubble positions. These experiments demonstrate a clear dependence of both collapse parameters on the porosity of the boundary but indicate limited sensitivity at high and low porosity values. Surprisingly, the position of the bubble, over either a hole or a solid part of the boundary, does not significantly influence the displacement or rebound strength.