Study on the physics during the final stageof bubble collapse

发展了一种改进的幽灵流体方法，用于研究具有非平衡相变的非球形气泡崩塌，采用自适应分区网格，其网格分辨率随气泡的体积变化和平移运动而变化，从而成功地捕捉到了精细的界面结构。气泡界面上的压力和温度不连续被幽灵流体捕捉到。该方法已被应用于激波-气泡相互作用下的气泡坍塌和流道中气泡云的坍塌等。实验研究了气液两相文丘里流动中气泡的破裂和压力波的传播。阐明了非平衡相变对气泡破裂的影响，以及气泡混合物中伴随气泡振荡的压力波特性。

An improved ghost fluid method has been developed for understanding nonspherical bubble collapse with nonequilibrium phase transition.We have succeeded in capturing the fine interfacial structure by using adaptive zonal grids in which the grid resolution is changed according to the volume change and translational motion of a bubble. The pressure and temperature discontinuity at the bubble interface has been captured sharply with ghost fluids. The method has been applied to the bubble collapse by shock-bubble interactions and to the collapse of a bubble cloud in a channel, and so on. The bubble collapse and the propagation of pressure waves in gas-liquid two-phase Venturi flows have also been investigated, experimentally. The influence of nonequilibrium phase transition on bubble collapse and the characteristic of pressure waves with bubble oscillations in bubble mixtures have been clarified.