Research on the bubble collapse behaviors near dual cylinders within confined spaces

This paper investigates the bubble collapse characteristics near dual cylinders within confined spaces. Firstly, the impacts on the bubble morphology, with respect to the bubble positions and the cylinder spacings, are explored using high-speed photography experiments. Subsequently, based on the circle theorem, the liquid velocity field is qualitatively analyzed and compared with the experimental bubble interface motion. Finally, employing the Kelvin impulse theory, an analysis of the variation in Kelvin impulse at various cylinder spacings is conducted, which shows good consistency with the bubble centroid movement. The main conclusions are summarized as follows: (1) High-velocity regions are observed on both sides of the bubble. Low-velocity regions are observed between the bubble and cylinders. As the cylinder spacing and the bubble abscissa increase, the liquid velocity in the high-velocity regions decreases, and the low-velocity regions expands. (2) The characteristics of the bubble cross-sectional roundness, interface displacement, and cross-sectional area are significantly affected by the cylinder spacing and the bubble abscissa. (3) As the bubble abscissa increases, the Kelvin impulse intensity initially rises rapidly and subsequently declines gradually to a fixed value. As the cylinder spacings increases, the Kelvin impulse intensity decreases.