Vortex dynamics and wall shear stress from bubble collapse near a particle and a wall

Abstract

Vortex dynamics and wall shear stress induced by cavitation bubble oscillations under the influence of particles are numerically investigated with the aid of a compressible two-phase flow solver in OpenFOAM. The generation, evolution, and disappearance of vortexes for three jet behaviors are discussed in detail. The variations of wall shear stress induced by the jets and the vortexes during the bubble oscillations are analyzed. Numerical results reveal that vortex dynamics is related to bubble evolution and jet behavior. After the jet pierces the bubble, an annular vortex with the bubble as the vortex core is generated by the bubble collapse. For the bubble that collapses near the wall, it generates multiple small vortexes near the wall and causes discontinuities in the wall shear stress. For the bubble that collapses away from the wall, it does not generate vortexes near the wall, and its oscillations cause the wall shear stress to vary periodically with different periods. In addition, the wall shear stress at the axis of symmetry increases abruptly when the jet hits the wall.