New coalescence and breakup kernels for air-water and steam-water pipe flows

New coalescence and breakup rate kernel functions are tested in the frame of MUSIG approach for developing bubbly flows inside a vertical pipe. Two test cases are investigated in this work, one from the MTLoop air-water experiment and the other from TOPFLOW steam-water experiment. Both of them demonstrate that consideration of bubble coalescence and breakup can improve predictions considerably. Furthermore, the new models are able to deliver reliable results in both the air-water and steam-water cases without need to adjust the constants, while the widespread model combination predicts too large coalescence and breakup rates. However, there is still a long way to go before a generally-applicable set of constants in the new models is achieved.