On the modelling of multiphase turbulent flows for environmental and hydrodynamic applications

The paper examines a selection of well-established prediction methods employed for the modelling of multiphase turbulent flows presented in typical environmental and hydrodynamic applications. The main objective is to provide a basic understanding of the subject with a deliberate intention to simplifying the presentation. Turbulence is approached on the basis of the conventional one-point closure context. The experience gathered by the author and by others with various predictive strategies all based on the Eulerian-Eulerian (field description) and the Eulerian-Lagrangian methods are discussed and summarized: the goals, limitations. and required developments are described. Typical applications of each calculation method are presented, in which the interaction between the transported dispersed-phase and the field turbulence is treated on the basis of both one-way and two-way coupling. The case studies in question include aerosol production and transport over the oceans, pollutant dispersion in the atmospheric surface layer, hydrometeor impact on urban canopies, sedimentation of active sludge in secondary water clarifiers. and mixing and circulation within confined bubble plumes. Analysis of the various models reveals that for most of the reported applications the Reynolds averaged Navier-Stokes approach is inherently ill-posed and should be transcended by the promising large-eddy simulation concept. (C) 2002 Elsevier Science Ltd. All rights reserved.