Bubble high-speed photography

A detailed study of the nucleation of ice by power ultrasoimd has been performed using a variety of high-speed photography systems with a particular focus on the influence of cavitation. The nucleation of ice has been shown to occur predominantly within the bubble cloud produced by a commercial ultrasonic horn. An investigation of a single oscillating bubble has confirmed that ice crystals are nucleated in the immediate vicinity of the bubble. 

The dynamic process of bubble collapse has been observed by Lauter-born and others by ultrahigh speed photography (105 frames/second) of laser generated cavitation (41). As seen in Fig. 4, the comparison between theory and experiment is remarkably good. These results were obtained in silicone oil, whose high viscosity is responsible for the spherical rebound of the collapsed cavities. The agreement between theoretical predictions and the experimental observations of bubble radius as a function of time are particularly striking. 

Planar imaging techniques like conventional photography and high-speed video imaging HSVI (Takahashi et al. 1992) have been used to visualise multiphase flows in mixed tanks. The observations about the mechanisms of bubble breakage, coalescence and wake effects can be used for the development of mechanistic bubble functions (Takahashi and Nienow 1993). HSVI requires plenty of well-directed light. 

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