Modeling Three Dimensional Bubble Dynamics Near Rigid Boundaries Using Boundary Integral Method

ABSTRACT

 

High speed liquid jet forms when a bubble collapses near a solid boundary. In this study, three-dimensional gas and acoustic bubble oscillation between two curved rigid plates are modeled based on the potential flow theory using boundary integral method (BIM). The bubble is incepted at different locations between the plates to investigate the eccentricity effects on the bubble shape, minimum bubble volume, centroid movement, jet formation, Kelvin impulse and bubble energy.

The modified Laplacian smoothing technique is implemented on the bubble surface during the jet development to reduce element distortion. Two situations have been considered, first, gas bubble with initial high pressure and second, Microbubble subject to planer traveling acoustic wave propagating either along positive or along negative x-axis. in both situations The models are validated with Spherical Bubble Oscillation equation at infinite fluid, with axisymmetric simulation as well as with the available experimental data.

We observed that the jet velocity increases and the number of jets are reduced from two to one as the bubble is horizontally shifted away from the centroid. When the bubble is incepted on the horizontal axisymmetric line the jet is horizontal. However, the jet direction changes as the bubble is incepted closer to one of the plates.

The pressure and velocity fields of the fluid surrounding the bubble are provided for better interpretation of the results. Finally, the comparison between gas bubble and acoustic bubble has been done.