정지된 유체에서 떠오르는 단일 기포와 벽 사이의 상호작용에 대한 실험적 연구

In studying gas-liquid flows which are very common in various industrial and natural flows, it is very important to characterize the interaction between the rising bubble and the solid wall in terms of understanding physics of gas-liquid flows and assisting numerical modeling. Thus, in this study, we investigate the effect of the wall on the dynamics of a rising bubble by varying (i) the distance between the bubble and the wall and (ii) the surf ace condition of the wall with high-speed imaging and two-phase particle image velocimetry. Experiments are conducted for a rising bubble whose Reynolds number is as high as about 800 in a rectangular water tank filled with stagnant water. For the wall, we consider acrylic, Teflon, and sponge which refer to no-slip, slip and permeable boundary conditions, respectively. Depending on the wall characteristics, the rising bubble shows quite different (e.g., sliding, bouncing, and departing) dynamics and their detailed mechanisms will be discussed.