Towards a theory of dynamics of a single cavitation bubble in a rigid micro-confinement

The nonlinear dynamics of a spherical bubble in the confined externally driven liquid cell is considered. It is shown that volume confinement strongly affects the manifestation of the classical cavitation Blake threshold. At relatively large liquid cell exposed to a tension exceeding cavitation Blake threshold, the cavitation bubble abruptly expands to a finite radius in contrast with explosive infinite bubble growth in bulk liquid. For smaller liquid cells, the corresponding finite radius of a cavitation bubble is getting smaller accordingly. At liquid cell size smaller than some critical one, the cavitation is completely suppressed by volumetric confinement. The generalized Rayleigh-Plesset equation for the confined bubble, accounting for mass of gas in the bubble, liquid compressibility, surface tension, and damping due to liquid viscosity in the cell is derived in which the liquid cell size is used as a driving parameter. Three possible regimes of bubble dynamics in confined liquid at different types of driving is studied. First, a simple nonlinear growth initiated by relatively weak liquid cell expansion when the cavitation Blake threshold is not reached yet. Second, an abrupt cavitation expansion with oscillatory transient when cavitation Blake threshold is reached. Third, multiple cavitation inception followed by cavitation vanishing at the periodic liquid cell expansion and contraction. In this case it is also found that for high driving frequency bubble dynamics in the confined liquid resembles the bubble dynamics in an unbounded liquid. (C) 2020 Elsevier Ltd. All rights reserved.