The inhomogeneous MUSIG model for upward polydisperse flows with new constitutive models for bubble coalescence and breakup

In the present study we propose new coalescence and breakup closures for the inhomogeneous multiple bubble size group (MUSIG) model. The major purpose is to consider bubble coalescence and breakup due to different mechanisms and to develop a general applicable constitutive model for CFD applications. For bubble coalescence the new model includes coalescence due to turbulence, laminar shear, wake entrainment and eddy capture. Bubble breakup mechanisms encompass turbulent fluctuation, laminar shear and interfacial slip velocity. The new models were implemented in ANSYS-CFX and applied to the case of turbulent air-water mixtures in a large vertical pipe (DN 200). Simulation results for the evolution of radial gas volume fraction, bubble size distribution were compared to as default used closure models of Luo & Svendsen and Prince & Blanch [1, 2] as well as TOPFLOW experimental data. Better prediction of bubble size distribution is accomplished.