Derivation of a macroscopic mixture model for two-phase turbulent flows

This article addresses the issue of reduced models to describe turbulent two-phase flows in industrial applications. A spatially-averaged mixture or drift-flux model is derived theoretically from local instantaneous Navier-Stokes description. Reynolds-averaging and space-averaging are applied successively. Between these two steps, a reduction achieved account for non-equilibrium between phases via algebraic relations. Applications this work not limited porous media but also include macroscopic descriptions high-shear regions developing near walls internal flows. Thermal effects, heat transfer at wall phase-change considered briefly discussed. The final describes evolution variables, including effects both sub-filter spatial variations, turbulence, velocity, pressure enthalpy. analysis provides bridges different approaches (local description, two-fluid model, model). It clarifies content each involved by defining them terms quantities. Turbulent fluctuations phase intermittency crucial mechanisms. Important void fraction dispersion diffusion; then, it necessary relative drift velocity orthogonal gravity induced complex interactions interfacial momentum transfer. (spatially-averaged) formulation open, sense that expressions various representing physics small scales provided; instead, physical origin paper meant as basis on which analyses imbalance assumptions closures can be assessed. CFD simulations provide information complement experiments technically challenging conditions processes essential yet difficult access experimentally (such transfers instance). Different kinds tested analyse their consequences model. In addition, new path calibrate closure laws propose opened based finer-scale descriptions. Guidelines use fine along with open derive relations either presented. They concern modelling average diffusion drop.