Journal of Fluid Mechanics

The final stage of the collapse of a cavitation bubble near a rigid wall

Sheguang  Zhang a1, James H.  Duncan a1 and Georges L.  Chahine a2
a1 Department of Mechanical Engineering, The University of Maryland, College Park, MD 20742, USA
a2 Dynaflow, Inc., 7210 Pindell School Road, Fulton, MD 20759, USA

Article author query
zhang s   [Google Scholar] 
duncan jh   [Google Scholar] 
chahine gl   [Google Scholar] 


During the collapse of an initially spherical cavitation bubble near a rigid wall, a reentrant jet forms from the side of the bubble farthest from the wall. This re-entrant jet impacts and penetrates the bubble surface closest to the wall during the final stage of the collapse. In the present paper, this phenomenon is modelled with potential flow theory, and a numerical approach based on conventional and hypersingular boundary integral equations is presented. The method allows for the continuous simulation of the bubble motion from growth to collapse and the impact and penetration of the reentrant jet. The numerical investigations show that during penetration the bubble surface is transformed to a ring bubble that is smoothly attached to a vortex sheet. The velocity of the tip of the re-entrant jet is always directed toward the wall during penetration with a speed less than its speed before impact. A high-pressure region is created around the penetration interface. Theoretical analysis and numerical results show that the liquid-liquid impact causes a loss in the kinetic energy of the flow field. Variations in the initial distance from the bubble centre to the wall are found to cause large changes in the details of the flow field. No existing experimental data are available to make a direct comparison with the numerical predictions. However, the results obtained in this study agree qualitatively with experimental observations.

(Published Online April 26 2006)
(Received November 17 1992)
(Revised May 13 1993)