Investigation of restricted bubble dynamics between double cylinders

This paper investigates restricted bubble dynamics between double cylinders. Typical bubble collapse phenomena between double cylinders are explored qualitatively through high-speed photographic experiments. Using Kelvin impulse theory, the Kelvin impulse and Bjerknes force acting on the bubble are analyzed. The characteristics of the bubble centroid motion are quantitatively analyzed and compared with the theoretical results. The following conclusions are drawn: (1) When the bubble is located close to the upper cylinder, during its collapse, the bubble has an inverted triangular shape that is symmetric about the inter-cylinder centerline, with its apex directed downward toward the lower cylinder. The contraction on the lower bubble side becomes greater with increasing cylinder radius. (2) The Kelvin impulse acting on the bubble exhibits a monotonically increasing trend with time, and the Bjerknes force reaches its peak in the initial growth stage and the final collapse stage. (3) As the cylinder radius increases, the Kelvin impulse and the Bjerknes force acting on the bubble become stronger, resulting in greater centroid displacement.