Analysis of bubble management at different gravity levels by means of an acoustic field

Multiphase flows management is a major challenge in many space applications given the different gravity levels involved. While many of the numerical investigations of liquid-gas phenomena deal with the radial bubble behavior and thus the heat exchange, only a few studies have been conducted on the translational motion of bubbles. We present a numerical investigation of the translational motion of gas bubbles im-mersed in a liquid that is subject to an acoustic wave at different gravity levels. In the computation, the equations for radial oscillation and translational motion are solved simultaneously. The dynamics of bub-bles at different gravity levels (from microgravity to hypergravity) are discussed. Bubbles can be trapped by the acoustic wave at levitation positions in different scenarios. The dependence of the levitation po-sition on the initial bubble position at different pressure amplitudes has been computed, giving rise to the bubble being directed to different nodes of the acoustic wave. The bubble radius also determines if and where the bubble levitates. We propose an analytical criterion for the capture of bubbles in a levita-tion position in terms of a new dimensionless parameter. The criterion is based on the balance between the average acoustic force and the buoyancy force. With the proposed criterion, the position of bubble levitation can be calculated analytically for any scenario. (c) 2021 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )

Automated summary

The numerical investigation focuses on the translational motion of gas bubbles immersed in a liquid subjected to an acoustic wave at different gravity levels. The study discusses the dynamics of bubbles at different gravity levels and proposes an analytical criterion for the capture of bubbles in a levitation position. This criterion is based on the balance between the average acoustic force and the buoyancy force, allowing the calculation of the bubble levitation position for any scenario.