Numerous studies have already shown that the process of cavitation can be successfully used for water treatment and eradication of bacteria. However, most of the relevant studies are being conducted on a macro scale, so the understanding of the processes at a fundamental level remains poor. In attempt to further elucidate the process of cavitation-assisted water treatment on a scale of a single bubble, the present thesis numerically addresses interaction between a collapsing microbubble and a nearby structure, that mechanically and structurally resembles a bacterial cell. A fluid-structure interaction methodology is employed, where compressible multiphase flow is considered and the bacterial cell wall is modeled as a multi-layered shell structure. The contribution of two independent dimensionless geometric parameters is investigated, namely the bubble-cell distance δ and their size ratio ϛ. The results show that local stresses arising from bubble-induced loads can exceed poration thresholds of cell membranes and liposomes, and that bacterial cell damage could be explained solely by mechanical effects in absence of thermal and chemical ones. Microstreaming is identified as the primary mechanical mechanism of bacterial cell damage, which in certain cases may be enhanced by the occurrence of shock waves during bubble collapse.
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