Numerical Investigation of Rising Bubbles through a Stratified Liquid-Liquid Interface

The buoyancy-driven rise of gas bubbles and their passage through an interface between two stratified immiscible liquids is an interesting phenomenon that is relevant in numerous engineering applications such as carbon sequestration, microfluidics, and bubble column reactors. Depending on the physical properties of the liquids (density, viscosity, and surface tension), and size and velocity of the bubbles, various interfacial flow regimes are attained such as penetration, entrapment, rupture and entrainment. The evolution of non-axisymmetric and non-spherical bubbles also significantly alters the rising dynamics. Most previous studies have focused primarily on a single bubble, assuming a two-dimensional (2D) axisymmetric evolution in a straight line. In the present effort, we use numerical simulations to study a ternary system with three-dimensional (3D) bubbles penetrating an interface between two stratified fluids. These simulations utilize the latest multiphase flow capabilities of Ansys Fluent such as Polyhedral Unstructured Mesh Adaption (PUMA), physics-based adaptive time-stepping, and advanced stabilization numerics. This work highlights some of our recent validation efforts and provides insights on bubble shapes, trajectories, and wake characteristics.