Stationary States before Sonoluminescence: Discrete Kinetic Approach

Abstract

Orientation-free discrete velocity model and diffuse-reflection boundary conditions are adopted together to solve the stationary noble-gas transport problem within a bubble in microdomains. Once the gas inside the bubble is dilute enough, we observe unusual very-high velocity (or pressure) and temperature fields for noble gases (corresponding to rather small Knudsen number: Kn ≤ 0.01, which is defined as the ratio of the mean free path of the noble gas to the bubble diameter) inside the bubble. The transport coefficients, or gas-velocity and gas-temperature fields (depending on Kn) are not uniform inside the bubble and there are sudden drops near the bubble wall. The latter, perhaps, is due to the heat-conducting bubble-wall. These results might give us some insights related to the initial state of the noble gases within the bubble before the on-set of sonoluminescence.