Models of Turbulent Flows and Particle Dynamics

摘要

Salient features of single-phase turbulent flow modelling are recalled first, including the closure problem, the statistical RANS models, the Lagrangian stochastic approach (one-point PDF method) together with its extension for near-wall turbulence, and the basics of Large-Eddy simulation (LES). In the second part of the chapter, two-phase dispersed turbulent flows in the Eulerian-Lagrangian approach are addressed. The issue of turbulent dispersion in RANS is succintly presented. Then, the subfilter dispersion in LES is discussed at length; functional and structural models are described, and some recent ideas about closures in terms of stochastic diffusion processes are discussed. Examples of computational results are presented for homogeneous isotropic and wall-bounded turbulence. At last, a specific modelling study of particle-laden channel flow is recalled where a low-order dynamical system with a reduced number of fluid velocity modes is constructed.