Numerical investigation on the interaction of planar shock wave with an initial ellipsoidal bubble in liquid medium

This paper performs numerical investigations on the interaction of shock wave with an ellipsoidal bubble in liquid medium. The governing equations, including the conservative Euler equations and the non-conservative transport equation of the liquid volume fraction, are discretized based on the finite volume method. A tangent of hyperbola for interface capturing (THINC) interface reconstruction scheme is employed for the phasic densities and the liquid volume fraction to maintain the interface sharpness. The major-axis (z-axis) of the bubble is parallel to the incident planar shock wave. Different collapse behaviors are observed for two ellipsoidal geometries, named as the disk-like bubble and rugby-like one. Different collapse patterns of an initial ellipsoidal bubble are presented and the manifestation is that the transverse jets pierce the bubble differently, classified as along the centerline, off-centerline along the circumferential direction or along the meridian line if the aspect ratio is varied. For the disk-like bubble, it presents the strongest collapsing process under certain eccentricity, characterized by the highest water hammer pressure under the same incident shock strength. The second sheeting jet is an important factor that leads to the collapse of the remaining bubbles pierced by the first transverse jet.