Analysis of Bubbly Flow Generated by a Free Surface Piercing Cylinder Using OpenCV

The hydrodynamic characteristics of flow around a surface piercing cylinder is still important in the field of naval architecture and ocean engineering. Various experimental and numerical studies have been conducted on simple structures to develop engineering solutions for issues such as frictional and wave-making resistance, vortex-induced vibration (VIV), and noise generation. In particular, splash phenomena and noise generated around masts, which are critical components requiring specialized performance for military applications such as submarines, are directly related to the survivability of naval vessels. Therefore, a thorough hydrodynamic understanding of these phenomena and the development of methods to reduce underwater noise emissions are of paramount importance. This study provides an in-depth investigation of the flow characteristics occurring in the submerged region beneath a cylinder, with a particular focus on elucidating the effects of the mast-shaped structure on bubble generation and flow field variations. An OpenCV-based image processing technique was developed to quantitatively evaluate the amount of bubble generation, distinguish between bubbles of different sizes, and track their trajectories. Furthermore, the bubble generation patterns were analyzed under various flow velocity conditions.