Migration dynamics of an initially spherical deformable bubble in the vicinity of a corner

Abstract

Three-dimensional numerical simulations are performed to study the migration dynamics of a deformable bubble that is spherical at an initial time near a corner formed by two vertical walls. Near-wall dynamics of this rising bubble are studied by investigating its path, wake, shape and velocity. A finite volume approach coupled with VOF (volume-of-fluid) method is adopted to solve the incompressible Navier–Stokes equation and track the gas–liquid interface. From the study, it is found that bubble inertia is dictated by initial bubble–walls interaction as bubble progressively migrates away in a diagonal direction from both the vertical walls in three-dimensional space. This influenced bubble inertia, in turn, affects the conformity of the bubble to a specific bubble regime. Five regimes are identified based on the bubble's migrating trajectory among which three of them are fully developed-steady, zigzag, and spiral and two of them are transitional-steady to zigzag and zigzag to spiral. The point of complete transformation of bubble from steady to zigzag transition to fully developed path instability is evaluated by varying a certain dimensionless parameter, Galilei number Ga. It is found that the path instability occurs at a lower Ga than what it is for the unbounded situations, and the onset of planar zigzag motion is not the result of vortex shedding rather the critical amount of wake accumulation on bubble surface and bubble inertia modulated by walls. Furthermore, the overall dynamics found in the current study show distinguishable characteristics when compared to single wall and unbounded situations.