Abstract
We perform high-resolution numerical simulations of three-dimensional dynamics of an elongated bubble in a microchannel at moderate Reynolds numbers up to 1800. For this purpose, we use the coupled Brinkman penalization and volume of fluid methods implemented in the open-source framework Basilisk. The new results are validated with available experimental data and compared with previous numerical and theoretical predictions. We extend existing results to regimes with significant inertia, which are characterized by intense deformations of the bubble, including cases with azimuthal symmetry breaking. Various dynamical features are analyzed in terms of their spatiotemporal characteristics, such as frequencies and wavelengths of the bubble surface undulations and vortical structures in the flow.
Highlights
Understanding the flow of viscous liquid containing gas bubbles is a classical and challenging problem in multiphase fluid dynamics
New theoretical predictions are in good agreement with the experiments, and as we show in the sections below, their predictions are in good agreement with our numerical simulations in parameter regimes corresponding to the steady or quasi-steady dynamics of the bubble
The equations above are solved using the open-source software Basilisk [32], which uses the Cartesian grid with adaptive mesh refinement (AMR) and the volume of fluid method (VOF)
Summary
Understanding the flow of viscous liquid containing gas bubbles is a classical and challenging problem in multiphase fluid dynamics. The simulations are carried out using the numerical algorithm we proposed in [31], which is implemented in the open-source software Basilisk [32] It allows for highly accurate simulations using effective mesh adaptation to resolve all multiscale features of the flow, especially the thin-film flow between the bubble and the wall. In these sections, comparisons with the experiments and prior work are presented, and the observed dynamics are explained in terms of the oscillation characteristics of the bubble and of the thin film between the bubble and the tube wall.
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