Numerical study on the single bubble rising behaviors under rolling conditions

Abstract

The accurate prediction of bubbles rising characteristics is very important for the two-phase flow and heat transfer calculation, especially under the ocean conditions. The additional force will be introduced and applied on the bubbles and the bubble behaviors is different from that under the stationary conditions. In present work, two methods, the additional force and dynamic mesh of Arbitrary Lagrangian–Eulerian (ALE) method, are compared, the result shows these two methods are in accordance to calculate the effect of rolling. Then Volume of fluid (VOF) and ALE method have been used to calculate the single bubble rising characteristic under rolling conditions. Results show that sphere bubble, ellipsoidal bubble and sphere cap bubble exist during the whole rising process and the deformation is becoming larger with the increase of bubble size. The bubble tends to move laterally and periodically under rolling conditions. The period of lateral movement is in accordance with the rolling period and the amplitude of the bubble is proportional to the rolling amplitude. Also, larger bubbles have the higher rising velocity than the small ones. The bubble rising characteristics are determined by not only the rolling motion but also the surface oscillation under rolling conditions.