Pulsations of double bubbles near a rigid wall under the driving of ultrasound

In real applications of ultrasonic cavitation, the cavitation bubbles perhaps locate at the region around rigid wall. Investigation of bubble pulsation near the wall is beneficial to utilize cavitation. The dynamics of bubbles near rigid wall is studied in this paper. The results reveal that if the distances of two bubbles to the wall are the same, with the increase of the distance, reflection of the rigid wall falls down, and the ratio of the maximum radius to the minimum radius of each bubble in pulsation (i.e. compression ratio) increases; the compression ratio of the bubble with a fixed position decreases when it is approached by another bubble with a varying distance from the wall; Increasing the equilibrium radius of a certain bubble leads to the decrease of the compression ratios of the two bubbles. Moreover, this paper also discusses the relationship of the bubble compression ratio with the angle between the connecting line of two bubble centers and the wall surface when the spacing between the two bubbles is fixed.