Effects of vapour pressure on the motion of cavitation bubble

Two models of bubble dynamics with constant vapour pressure and vapour content were newly developed. The mass flux of water vapour at bubble wall was simplified to facilitate the analysis. Based on these two models and the approximation of the mass flux, more simplified equations corresponding to the models were deduced from dynamic equation of bubble corrected by Sochard et al. MATLAB and the Runge–Kutta algorithm were applied to calculate and analyse the dynamical behaviour of cavitation bubbles under an ultrasonic field. Numerical results reveal that bubbles under the constant vapour pressure model exhibit larger amplitudes and move more violently to generate acoustic cavitation effect than the constant vapour content model. Nevertheless, the kinetic characteristics of bubbles under the constant vapour content model are similar to those of bubbles without water vapour. Moreover, vapour content exerts certain influence on the maximum radius, minimum radius and collapse intensity of bubbles.