Numerical simulation of bubble interactions

Introduction Single bubble dynamics has been intensively investigated theoretically, experimentally and numerically during the last century [1]. Analysis of the interactions between bubbles in a cavitating flow or the interactions among an individual bubble pair has risen from the demand of a more comprehensive understanding of bubble dynamics. When a bubble is induced near an interface by a laser beam, it collapses in an asymmetric way. If the interface is a rigid surface, a liquid jet of velocity in the order of 100 m/s is induced and hits onto this rigid surface. This is a source of cavitation erosion but not the most promising method for an active control of jet formation. If the bubbles are arranged into a pair, their dynamics is governed by three parameters: the phase difference, the initial energy and the distance between them. Through adjusting these parameters, both the jetting direction and the jetting intensity can be controlled. This is of particular interest for cell transfection, i.e. the introduction of nucleic acids into living cells [2, 3]. In order to investigate the roles of these three parameters in the jetting formation, numerical simulations are performed in this paper and compared with previous experimental results [4]. The insight gained from the numerical simulations will be helpful in guiding further experimental investigations.