Liquid drainage in static foam: Analogy with liquid drainage through packed bed

Abstract

High intensity ultrasonic vibrations are known to be efficient at destabilizing stationary foams. In this paper, the effect of the application of ultrasonic vibrations generated by an ultrasonic bath has been studied on the drainage of static foam. The vibrations are found to enhance the drainage rate of the foam and the model could be extended to correlate these drainage rates. This model can also be used to predict the variation in the foam cell size and shape factor during drainage. The effect of type of sparger and column diameter on the drainage rate has been studied. The rate of foam collapse depends on the foam cell size, which in turn depends on the sparger used for foam generation. The foam drainage and collapse rates were found to increase with the decrease in the column diameter.