Implosion of spherical and cylindrical air cavities

The article of record as published may be found at https://doi.org/10.1007/s41939-020-00074-2Collapses of various air cavities (or bubbles) surrounded by much higher water pressures were investigated using the analytical equations as well as the finite element analysis (FEA) to understand the characteristics of the collapsing cavities and the propagation of shock waves resulting from the collapse. Both spherical and infinitely long cylindrical cavities were considered, while the initial radius of the cavity and the water depth were varied. The study examined the collapsing speeds of the cavities to their minimum sizes, the times to reach the minimum sizes, the resultant maximum pressures in the cavity, and the propagating pressure profiles emitted from the collapsed cavities. The FEA solutions were compared to analytical equations from different theories when the latter was available. Empirical equations were also developed with the guidance of the theories and the observation of the FEA results for those parameters examined in the study, so that the characteristic behaviors of collapsing cavities and their generation of shock waves could be better understood and predicted.Y.W. Kwon acknowledges the financial support from the Solid Mechanical Program of Office of Naval Research.Identified in text as U.S. Government work.This work was supported by Office of Naval Research (ONR