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The first part aims at providing the physical and theoretical framework of the analysis of density variations in fully turbulent flows. Its scope is deliberately educational. §In the second part, basic data on dynamical and scalar properties of variable density turbulent flows are presented and discussed, based on experimental data and/or results from direct numerical simulations. This part is rather concerned with a research audience. §The last part is more directly devoted to an engineering audience and deals with prediction methods for turbulent flows of variable density fluid. Both first and second order, single point modeling are discussed, with special emphasis on the capability to include specific variable density / compressibility effects.In various industrial applications, turbulence can be affected by density variations resulting from different origins acting simultaneously. This monograph is intended as a first attempt to address variable density fluid turbulence in a unifying manner. It is based on a rational approach, developed along a gradual analysis of the complexity resulting from density fluctuations in turbulence. §The first part aims at providing the physical and theoretical framework of the analysis of density variations in fully turbulent flows. Its scope is deliberately educational. §In the second part, basic data on dynamical and scalar properties of variable density turbulent flows are presented and discussed, based on experimental data and/or results from direct numerical simulations. This part is rather concerned with a research audience. §The last part is more directly devoted to an engineering audience and deals with prediction methods for turbulent flows of variable density fluid. Both first and second order, single point modeling are discussed, with special emphasis on the capability to include specific variable density / compressibility effects. §The main topics are: §-Physical aspects of variable density turbulent flows, §-General equations and Classification of variable density turbulent flows, §-Statistical averaging in variable density fluids motions, §-Velocity and scalar structure in passive contaminant turbulence, §-Basic Mechanisms in low speed variable denisty turbulence, §-The high speed free shear layer and Single point closure in variable density fluid turbulence. §The book is intended for a rather wide audience, including postgraduate students, researchers and engineers. Variable Density Fluid Turbulence should be of interest to various domains of Mechanics, Energy and Environmental Fluid Dynamics, such as Aerodynamics, Turbulence, Compressible flows, Heat and Mass Transfer, Machinery Fluid Mechanics, Thermal sciences
