Effects of Bubble Generation Frequency and Rise Distance on the Structure of Rising Bubbles Along an Inclined Flat Wall

The bubble-bubble interaction of two spherical bubbles rising along an inclined flat wall was investigated experimentally. The relative position of all pairs of two bubbles was statistically analyzed. It was observed that as the two bubbles rose along the wall and the rise distance increased, the bubble alignment changed from vertical to horizontal. It was also observed that the bubble alignment changed from vertical to horizontal with an increase in the bubble generation frequency. This suggests that both bubble generation frequency and rise distance are key factors in determining the formation of bubble clusters. The comparison of obtained 2D discrete pair distribution functions between different bubble generation frequencies and rise distances showed some similarities between them; the bubble accumulation for low bubble generation frequency at large rise distance was similar to that for high bubble generation frequency at small rise distance. The correlation coefficient between them was found to be more than 0.8 in some cases.