Browsing by Author "Akhatov, I."

A strong laser pulse that is focused into a liquid produces a vapor cavity, which first expands and then collapses with subsequent rebounds. In this paper a mathematical model of the spherically symmetric motion of a laser-induced bubble is proposed. It describes gas and liquid dynamics including compressibility, heat, and mass transfer effects and nonequilibrium processes of evaporation and condensation on the bubble wall. It accounts also for the occurrence of supercritical conditions at collapse. Numerical investigations of the collapse and first rebound have been carried out for different bubble sizes. The results show a fairly good agreement with experimental measurements of the bubble radius evolution and the intensity of the outgoing shock wave emitted at collapse. Calculations with a small amount of noncondensable gas inside the bubble show its strong influence on the dynamics. (C) 2001 American Institute of Physics.

Single cavitation bubble luminescence induced by laser in contrast to single bubble sonoluminescence has no need in a sound field for a strong collapse and for light emission, The cavitation bubbles are produced by focused laser light and make the single strong collapse. As shown experimentally. the number of emitted photons from cavitatior luminescence is much greater than it was observed in sonoluminescence due to the large bubble size during the final stage of co lapse. To describe the process of laser-induced bubble collapse a mathematical model is used, which is based upon the spherically symmetric motion including compressibility, heat and mass transfer effects. The basic results of the numerical solution are presented for the bubbles with maximum radii of about I mm. According to the observed results the minimum bubble radius in collapse is about 15 mum, and the mass decreases up to 5% of the initial value. Calculations with a small amounts or noncondensable gas inside the bubble predict its strong influence on the dynamics. As shown numerically the theoretical model gives a good agreement with experimental measurements. (C) 2002 Elsevier Science Inc. All rights reserved.