Numerical simulation of plane bubble plume by vortex method

Abstract

This study is dealing with the two-dimensional numerical simulation of a plane bubble plume experimentally investigated by Alam and Arakeri. A vortex method for gas—liquid two-phase flow, proposed by the authors in a prior paper, is applied for the simulation. The method simulates the bubble motion and the induced liquid flow by the two-way coupling approach. In a tank containing water, small hydrogen bubbles are released from an electrode placed on the base of the tank. The bubbles, rising due to the buoyant force, cause the vortical flow of water. The existing numerical methods, such as the finite-difference method and the finite-volume method, compute the bubble plume with regard to the velocity field. But the vortex method calculates directly the vorticity field. Therefore, it promises to simulate successfully the vortical structure predominating the bubble plume. The present simulation makes clear that the meandering behaviour of bubble plume is caused by the large-scale eddies induced by the rising bubbles. The effect of bubble flowrate on the meandering behaviour in the simulation is confirmed to agree well with the experiment. It is also demonstrated that the time-averaged water velocity on the horizontal sections satisfies the similarity distribution when the bubble flowrate is low. These indicate that the authors’ vortex method is indeed applicable to the analysis of plane bubble plume.