On the evolution, generation, and regeneration of gas cavitation nuclei

Abstract

Recently a new cavitation model has been proposed in which bubble formation in aqueous media is initiated by spherical gas nuclei stabilized by surface-active membranes of varying gas permeability. By tracking the changes in nuclear radius that are caused by increases or decreases in ambient pressure, the varying-permeability model has provided precise quantitative descriptions of several bubble counting experiments carried out with supersaturated gelatin. The model has also been used to calculate diving tables and to predict levels of incidence for decompression sickness in a variety of animal species, including salmon, rats, and humans. Although the phenomena involved are in some sense dynamic, the model equations, in their present form, are essentially static and can be derived by requiring mechanical or chemical equilibrium at each setting in a rudimentary pressure schedule. In this paper, we examine the time dependence of the evolution of an individual nucleus from one equilibrium state to another, and we then investigate a statistical process by which the equilibrium size distribution of an entire population of nuclei may be generated or regenerated.