Breakup dynamics of initially non-spherical rising bubbles*

The recent emergence of new immersed energy storage systems such as the underwater compressed air energy storage (UWCAES) system requires the development of risk analysis studies associated with the potential accidents that can occur. For instance, a rupture of the pipe connecting the energy conversion platform to the storage tanks would generate a bubble plume rising rapidly to the surface by means of gravity. The dynamics of the plume itself depends on the interaction mechanisms between the bubbles composing it, including breakup and coalescence. 

To improve the understanding of the breakup phenomenon, DNS simulations of single air rising bubble in water are performed using the in-house ARCHER solver. Different initial shapes of bubble are investigated (spheroid, torus, and spherical cap), so that the variety of bubble shapes in the plume is considered. Focus is made on large bubbles belonging to the central breakup regime.

The bubble dynamics is analyzed in terms of shape evolution and related to the breakup process. It is shown that the initial shape influences the breakup dynamics. The breakup time and distribution of daughter bubbles are also extracted to help design a model for the breakup due to interfacial instability that will be included in a Population Balance Model.