Numerical investigation of axisymmetric bubble dynamics from a submerged circumferential slit on the cylinder

The boundary element method is adopted to study the ventilating axisymmetric bubble growth from a circumferential slit in a submerged cylindrical wall under vertical flow conditions in this paper. During the bubble growth, mesh subdivision and smoothing techniques are adopted in order to optimize mesh topology. In this study, the effects of inflow velocity, surface tension coefficient, ventilation rate and slit width on the bubble development process are studied. The results show that the bubble shape is mainly affected by the inflow velocity and the surface tension coefficient, the inflow velocity promotes the downward movement of the lower intersection point of the wall and bubble, meanwhile, the surface tension inhibits it. The effect of slit width is mainly reflected in the initial stage of the bubble development. And the bubble size basically increases as the ventilation rate increases. In addition, the effects of the Froude number, Weber number, and ventilation coefficient on bubble growth are analyzed. The maximum dimensionless length and thickness of the bubble increase with the increase of the Froude number and decrease with the increase of the Weber number. As the ventilation coefficient increases, the length decreases first and then stabilizes, the thickness decreases first and then increases. (C) 2020 Elsevier Ltd. All rights reserved.