Cavitation bubbles could also be called as inertial bubbles because of their oscillation due to the pressure difference between inside and outside. After the passage of an underwater shock wave, the violent collapses of the bubbles are induced and could produce stronger mechanical and biochemical actions so that the marine bacteria around them are inactivated by those productions. In the present study, cavitation inertial bubbles are observed behind multiple waves in a narrow water chamber after an electric discharge is triggered and then interacts with underwater reflected shock waves from the water chamber. The sterilization effects of only these oscillating bubbles and cavitation-shock interaction are investigated by bio-experiments of marine Vibrio sp. The results show that a high sterilization is obtained in the case of the cavitation-shock interaction. Furthermore, the chemical action of free radicals mainly contributes to inactivating the marine bacteria. The generation of the hydroxyl (OH) radicals is clarified by measuring the concentration of H2O2. Subsequently, we focus on a theoretical analysis of the generation condition of the OH radicals by a bubble dynamic model consisting of an oscillation model and an impact model. Finally, the theoretical estimation by the bubble dynamic model is discussed under the conditions of the present experiments. As a result, there is a possibility of effective sterilization by the cavitation-shock interaction without the supply of air microbubbles.
ASJC Scopus subject areas
- Physics and Astronomy(all)