Relaxation and power spectra of low-frequency fluctuations in foams

The dynamics of foam formation in a water-glycerin solution was studied to establish the relationship between the relaxation characteristics and the fluctuation power spectrum for a stochastic process. Foaming occurred during the dissociation of the gas-saturated solution and during bubbling of the solution through a porous filter. Two types of relaxation of the foam–exponential and power-law–were revealed. The power-law type of relaxation was observed upon exposure to ultrasound. Relationships between the type of relaxation and the distribution of lowfrequency fluctuations and power spectra was established.