Investigation of bubble dynamics in a micro-channel with obstacles using a conservative phase-field lattice Boltzmann method

Abstract

Simulating bubble dynamics impacting on obstacles is challenging because of large liquid-to-gas density ratio and complex interface deformation. In this study, a conservative phase-field model, based on a modified Allen–Cahn equation, is employed to accurately capture the bubble interface, and the lattice Boltzmann model is applied to solve the flow field. The bubble rises under the influence of buoyancy force and surface tension force, and complex topology changes, such as rotation, breakup, and squeeze deformation, are predicted in the presence of obstacles. Three dimensionless numbers, including Reynolds, Eötvös, and Morton numbers, are used to characterize bubble dynamics, and two shape indicators, including the revised Blaschke coefficient and the oblateness degree, are introduced to obtain a more systematic assessment of the bubble shape. Effects of flow parameters and obstacle geometries on bubble dynamics impacting on obstacles are investigated to render a quantitative investigation with physical insights. Model extension to the 3D case, the low-viscosity flow and non-pure fluid is further remarked, which can shed light onto future development of physically informed models for predicting the bubble behavior in more real scenarios.