Mass and Heat Transfer in Turbulent Flows

Equation of mass and heat transfer. In mathematically describing transfer of a passive admixture in a turbulent stream, the admixture concentration and the fluid velocity components are represented as 

Mass Transfer in Films, Tubes, and Boundary Layers 

The introduction of the average and fluctuating components by relations (3.1.36) followed by the application of the averaging operation made it possible, under some assumptions, to obtain the following equation for the average concentration of the admixture [276] from Eq. (3.1.1)  

Here -C V is the turbulent (eddy) flux of the admixture. This vector can be determined using some closure hypothesis, based, as a rule, on empirical information. 

By analogy with Boussinesq s ideas about transfer of momentum, it is often assumed for transfer of a substance that 

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