Bubble Nucleation in Supersaturated Fluids

摘要

An understanding of the physics of bubble formation is of importance in such diversified endeavors as propeller design, fluid flow, undersea medicine, and the brewing of beer. While the properties of preformed bubbles are well understood, relatively little is known about the physical mechanisms responsible for their creation. This publication reports on the principal results of a program designed to elucidate the nature of the bubble nucleation process, and it briefly explores the applicability of the findings to decompression sickness. An introduction to the physics of bubbles is followed by an outline of the theory of homogeneous nucleation. The results of an experimental program in which transparent gelatin was used to stabilize bubbles against floatation are reported. The existing models of cavitation nuclei are classified into four major groups, and each group is briefly discussed. The principal thesis of this work is advanced: that the cavitation nuclei present in common fluids consist of spherical gas phases encased in monomolecular skins of surface-active molecules. The surface-active material forming the skin of the nuclei observed in gelatin is shown to be similar to several commonly occurring surfactants, namely the saturated lecithins and phosphatidylethanolamines. The final chapter explores the application of the results of this research to the study of decompression sickness.