Numerical Calculation of Laser-Produced Bubble near a Solid Boundary until the Second Collapse

The violent motion of cavitation bubble near a solid boundary is treated by a newly developed numerical code based on the CIP (Cubic Interpolated Propagation) method. This is the first study to successfully simulate the repetitive collapses and rebounds of bubbles with the penetration of microjets until the second collapse while maintaining toroidal shape. The obtained gas-liquid interfaces show similar tendency to bubble shapes observed in past experimental studies, although phase change, surface tension and viscosity are neglected. The key factor of this flow field is the density difference between gas and liquid. The velocity of microjet and resulting water hammer pressure are calculated successfully. However no shock wave appears from the collapsed bubbles in the present study, which suggests that an appropriate model for highly-compressed gas is important for tempestuous two-phase flow. This study indicates a high possibility of using the Euler-type numerical code to calculate such complicated two-phase problems and also suggests which factor is dominant in the cavitation bubble dynamics.