In the paper the paths of bubbles emitted from the brass nozzle with inner diameter equal to 1.6 mm have been analyzed. The mean frequency of bubble departure was in the range from 2 to 65.1 Hz. Bubble paths have been recorded using a high speed camera. The image analysis technique has been used to obtain the bubble paths for different mean frequencies of bubble departures. The multifractal analysis (WTMM - wavelet transform modulus maxima methodology) has been used to investigate the properties of bubble paths. It has been shown that bubble paths are the multifractals and the influence of previously departing bubbles on bubble trajectory is significant for bubble departure frequency fb > 30 Hz.

In the experiment, bubbles were generated from two brass nozzles with inner diameters of 1.1 mm. They were submerged in the glass tank filled with distilled water. There have been measured the air pressure fluctuations and the signal from the laser-phototransistor sensor. For analysis of the pressure signal the correlation (the normalized cross - correlation exponent) and non-linear analyses have been used. It has been shown that hydrodynamic interactions between bubbles can lead to bubble departure synchronization. In this case the bubble departures become periodic. The results of calculation of correlation dimension and the largest Lyapunov exponent confirm that hydrodynamic bubble interactions observed for 4 mm spacing between nozzels cause the periodic bubble departures from two neighbouring nozzles.

In this paper, the dynamics of an acoustic bubble with a constant charge in compressible liquid are investigated numerically, which is based on the Gilmore-NASG model to estimate the radial oscillations. The cavitation effects are enhanced due to the presence of the charge on the bubble surface. The obtained results from the present model are compared with that calculated by the previous model within a wide range of parameters (e.g., charge, acoustic pressure amplitude, ultrasound frequency, and liquid temperature). The similar influences of these parameters on bubble collapse intensity can be observed from both models. Since the present model fully considers the compressibility of gas and liquid, it can be applied to a wider parameter range and leads to the larger predicted values. The research in this paper can provide important insights about the effects of charge on bubble dynamics and the acoustic cavitation applications (e.g., sonochemistry, water treatment, and food industry).