(428a) Mixing and Turbulence in Gas-Liquid Systems: Bridging First Principle and Application Needs

Most industrial systems in the chemical, process and nuclear industry are multiphase in nature. Multiphase models in Computational Fluid Dynamics that account for mixing, turbulence and interfacial exchange behavior offer the potential to transform the design of more efficient chemical and process systems. The effectiveness of its application relies on the accuracy and predictive ability of the models, which must, at the same time be integrated into an effective computational tool and allow optimal flexibility and scalability.

A large effort at MIT has been devoted to the development of a second-generation of multiphase- closures. In the past different groups have proposed different balances of drag, lift, turbulent dispersion and wall lubrication forces to represent the same set of experiments, producing comparably incomplete agreement with the experimental data, on a very limited set of conditions.

In this paper we will present a new set of momentum closures, where the near wall effects are included as a regularization of the turbulent dispersion based on the analytical near wall void fraction distribution, and the lift inversion is accurately predicted from the instability of bubble motion. The new formulation is assessed on a very comprehensive set of conditions, spanning the whole bubbly flow regime over a wide range of Eötvös and Reynolds numbers and showing a very good agreement with experimental data.