GAS-VAPOR BUBBLE DYNAMICS AND HOMOGENEOUS SONOCHEMISTRY

This paper deals with modelling of homogeneous reactions enhancement b y ultrasound. First a survey of bubble dynamics is proposed, then a co nvenient model is carried out assuming pressure uniformity, but includ ing heat and mass transfer (interdiffusion of gas and vapour inside th e bubble and vapour-liquid phase change at the interface). The numeric al solution consists in an orthogonal collocation using Chebychev poly nomials for spatial integration together with a Gear method for time i ntegration. At the end of a collapse, all the reactions of dissociatio n yielding free radicals in the bubble are assumed at thermodynamic eq uilibrium so that a local minimization of Gibbs free energy provides t he local composition in the bubble. Influence of physico-chemical prop erties of gas and liquid as well as experimental conditions on maximum temperature and free radicals concentration have been then derived. ( C) 1997 Elsevier Science Ltd.