Non-linear analysis of air pressure fluctuations during bubble departure synchronisation

In the recent paper, non-linear methods of data analysis were used to study bubble departure synchronisation. In the experiment, bubbles were generated in engine oils from two neighbouring brass nozzles (with an inner diameter of 1 mm). During the experiment, the time series of air pressure oscillations in the air supply system and voltage changes on phototransistor were recorded. The analysis of bubble departure synchronisation was performed using a correlation coefficient. The following methods of non-linear data analysis are considered. Fast Fourier Transformation, autocorrelation, attractor reconstruction, correlation dimension, largest Lyapunov exponent and recurrence plot analysis were used to examine the correlation between bubbles behaviour and character of pressure fluctuations. Non-linear analysis of bubble departure synchronisation revealed that the way of bubble departures from two neighbouring nozzles does not depend simply on the character of pressure fluctuations in the nozzle air supply systems. The chaotic changes of the air pressure oscillations do not always determine the chaotic bubble departures.