Solubility inversion effects on diffusion from collapsing bubbles

Abstract

This work discusses the dissolution of gas bubbles in liquids subjected to a sudden pressure surge, as well as lending insight to studies on rectified diffusion. The bubble growth rates for rectified diffusion under isothermal conditions as predicted in previous studies are much lower than the rate found experimentally. The assumption of isothermal conditions can be justified only for infinite thermal diffusivity. For real gas bubbles collapsing in a large body of liquid, however,the thermal condition lies between the isothermal and adiabatic limits. Our analysis was undertaken to establish diffusion conditions for a collapsing cavity under the adiabatic limit. Contrary to the case of isothermal collapse, where the increased pressure (and hence the surface concentration) can result only in an outward diffusional flux, the solubility inversion effect for gases can cause first inward and then outward diffusional flux during the same phase of adiabatic collapse. In particular, when the heat of solution, [Delta]Hs, of the gas is less than ([gamma]BT0)/(1-[gamma]), where [gamma]=Cp/Cv, and B= gas constant), the diffusional flux changes direction at Even in situations where flux reversal does not occur, the net diffusional outflux during collapse is less in the adiabatic case than that in the isothermal case. Further descriptions of mass transfer from a bubble collapsing adiabatically in a large body of liquid are presented.