The initial motivation for the study was to gain deeper understanding into the background of emulsion preparation by ultrasound (cavitation). In our previous work (Perdih et al., 2019) we observed rich phenomena occurring near the liquid-liquid interface which was exposed to ultrasonic cavitation. Although numerous studies of bubble dynamics in different environments (presence of free surface, solid body, shear flow and even variable gravity field) exist, one can find almost no reports on the interaction of a bubble with a liquid-liquid interface. In the present work we conducted a number of experiments where single cavitation bubble dynamics was observed on each side of the oil-water interface. These were accompanied by corresponding simulations. We investigated the details of bubble interface interaction (deformation, penetration). As predicted, by the anisotropy parameter the bubble always jets toward the interface if it grows in the lighter liquid and correspondingly away from the interface if it is initiated inside the denser liquid. We extended the analysis to the relationships of various bubble characteristics and the anisotropy parameter.

Finally, based on the present and our previous study (Perdih et al., 2019), we offer new insights into the physics of ultrasonic emulsification process.

该研究的最初动机是对超声（空化）制备乳液的背景有更深入的了解。在我们之前的工作中（Perdih et al。，2019），我们观察到在暴露于超声空化作用的液-液界面附近发生的丰富现象。尽管存在许多关于在不同环境中（自由表面，固体，剪切流甚至可变重力场的存在）气泡动力学的研究，但几乎找不到关于气泡与液-液界面相互作用的报道。在目前的工作中，我们进行了许多实验，在油水界面的每一侧都观察到了单个空化气泡动力学。这些伴随着相应的模拟。我们研究了气泡界面相互作用（变形，渗透）的细节。如预期的那样 通过各向异性参数，如果气泡在较轻的液体中生长，则气泡始终向界面喷射，如果在较稠密的液体内部引发，则气泡始终远离界面。我们将分析扩展到各种气泡特征与各向异性参数之间的关系。

最后，基于当前和我们之前的研究（Perdih等人，2019），我们提供了对超声乳化过程物理学的新见解。