Dynamics of a spheroidal gas bubble near a rigid surface

Abstract

Non-spherical dynamics of a bubble during its axisymmetric collapse near a planar rigid wall is considered. The liquid surrounding the bubble is ideal incompressible, its flow is potential. The pressure in the bubble is uniform, and varying with respect to adiabatic law. At the beginning of collapse, the bubble is spheroidal, the liquid is motionless. A numerical technique is applied, which is based on a stepwise method in time for calculating the bubble surface movement and on the boundary element method. The initial stage of the bubble collapse till the moment of contact between some parts of the bubble surface (i.e., till losing its one-connectedness) is considered. The effect of the ratio of the semi-axes of the spheroidal bubble and the initial thickness of the liquid layer between the bubble and the wall on the bubble shape, the pressure and velocity fields in liquid are investigated. The region of the problem parameters (the distance from the wall, the bubble non-sphericity) is outlined, in which the bubble collapses with formation of a cumulative liquid jet impacting on the bubble surface part nearest to the wall. The liquid pressures resulting from the impact are estimated.

Single cavitation bubble dynamics in a stagnation flow

“…This kind of jet has been predicted for mildly ellipsoidal capped bubbles by Lauer et al. (2012) and Aganin, Kosolapova & Malakhov (2019), and was later shown to occur for axisymmetric cap-shaped bubbles in simulations and experiments by Saini et al. (2022).…”

“…A particularly interesting case is when the bubble takes the shape of a slender spherical cap during maximum expansion, which leads to a liquid jet that is directed away from the boundary. This kind of jet has been predicted for mildly ellipsoidal capped bubbles by Lauer et al (2012) and Aganin, Kosolapova & Malakhov (2019), and was later shown to occur for axisymmetric cap-shaped bubbles in simulations and experiments by Saini et al (2022). Here, a high-pressure region below the bubble forms that accelerates a liquid jet flow away from the surface.…”