ABSTRACT
We study, numerically and experimentally, three different methods to suppress the trajectories of strongly collapsing and sonoluminescent bubbles in a highly viscous sulfuric acid solution. A new numerical scheme based on the window method is proposed to account for the history force acting on a spherical bubble with variable radius. We could quantify the history force, which is not negligible in comparison with the primary Bjerknes force in this type of problem, and results are in agreement with the classical primary Bjerknes force trapping threshold analysis. Moreover, the present numerical implementation reproduces the spatial behavior associated with the positional and path instability of sonoluminescent argon bubbles in strongly gassed and highly degassed sulfuric acid solutions. Finally, the model allows us to demonstrate that spatially stationary bubbles driven by biharmonic excitation could be obtained with a different mode from the one used in previous reported experiments.
ABSTRACT
Laser-induced bubbles provide an effective vehicle to achieve high-energy concentrations and maximum temperatures in bubble luminescence phenomena. One limitation to the temperatures that can be achieved is the development of the Rayleigh-Taylor instability (RTI) during the instants previous to the bubble maximum compression. For a given fluid, the control parameters of the experiment are: the bubble maximum radius, the bubble ambient radius, the initial perturbations of the bubble, and the liquid pressure at infinity. In this work, experiments using laser-induced bubbles in a highly viscous phosphoric acid were performed in order to determine the achievable parameters values in the phase space. The effect of R(max), R(0), a(2)(i), a(3)(i), and p(∞) on the maximum temperature achieved by the gas contents inside the bubble were numerically determined. The results show for each static pressure an optimum region for maximum temperatures of the gas contents bounded by the RTI.
