Bubble breakup and coalescence models for bubbly flow simulation using interfacial area transport equation

This paper provides the state-of-the-art critical review on the modeled source and sink terms of the one-group interfacial area transport equation. The reviewed source and sink terms include models developed by Wu et al., Hibiki and Ishii, Hibiki et al., Yao and Morel, Park et al., Hibiki et al., Kataoka et al., Nguyen et al., Shen and Hibiki and Hazuku et al. The present critical review assesses major issues in modeling the one-group source and sink terms. Important conclusions are that the existing source and sink terms are not well-validated for developing and transient flows and the applicability of the source and sink terms to high pressure conditions such as prototypic nuclear reactor conditions has not been well-discussed. In view of these, coefficients of the source and sink terms in Hibiki and Ishii's model have been modified for their application to prototypic nuclear reactor conditions. In addition, approximated area-averaged source and sink terms due to turbulent diffusion and lateral migration are derived by area-averaging local source and sink terms due to turbulent diffusion and lateral migration developed by Kataoka et al. The role of the area-averaged source and sink terms due to turbulent diffusion and lateral migration on the interfacial area transport should be tested in a future study. This paper also overviews important model validation challenges to be addressed in a future study. The challenging model validation should address the model performance for various test sections and flow conditions. They are (1) the effect of channel size (small (or micro/mini)-to-large channels) on the interfacial area transport, (2) the scalability of the interfacial area transport equation to prototypic nuclear reactor conditions, (3) the effect of covariance due to phase distribution on the interfacial area transport, (4) the effect of inlet conditions on the interfacial area transport, (5) the applicability of the interfacial area transport equation to transient and developing flow conditions, and (6) the applicability of the interfacial area transport equation to various flow channels including a rod bundle.