Study of Sterilization Effects on Marine Vibrio sp. using Interaction of Cavitation with Shock Wave in a Narrow Water Chamber

When underwater shock waves are generated by an electric discharge in a narrow water chamber, the instant release of a great amount of energy causes the propagation of a shear wave in wall material with the deformation of the chamber wall. The shear waves produce decompression in water and result in the growth of bubble nuclei. Subsequently, those oscillating cavitation bubbles are exposed to the shock pressures, and thus free radicals and rebound shock waves are generated due to their violent collapses. Eventually, marine bacteria around them are inactivated by these productions. In the present study, we investigate the sterilization effects of these oscillating bubbles and cavitation-shock interaction by bio-experiments, respectively. Furthermore, the chemical action of free radicals on marine bacteria is discussed. The generation of the OH radicals is clarified by measuring the concentration of the H2O2. To estimate the generation condition of the OH radicals, a bubble dynamic model consisting of an oscillation model for the growth of bubble nuclei and an impact model to describe the cavitation-shock interaction is developed. Finally, the theoretical estimation by the bubble dynamic model is discussed under the conditions of the present experiments.