On the prediction of bubble size distribution and void fraction in vertical gas-liquid flows

Two-fluid modeling approach is considered as one of the most practical and accurate macroscopic formulation of handling bubbly flow systems. Nevertheless, in order to rigorously account for bubble-bubble interactions, the population balance equation (PBE) must be solved alongside with the continuity and momentum balance equations. Class method typified by the MUltiple SIze Group (MUSIG) model appears to be one of the most direct methods to solve the PBE using a finite series of discrete classes. In this paper, an alternative approach based on the direct quadrature method of moments (DQMOM) is investigated. In contrast to MUSIG model which requires a large number of classes to resolve the bubble distribution, the main advantage of DQMOM is that the number of moments to be solved is generally very small. Validation and assessment of the two population balance models are carried out against measurements of vertical bubbly flows for a range of flow conditions. Based on the present study, preliminary computed results have been found to compare very well against the experimental data as well as the numerical results predicted through the MUSIG mode