Flow Field in Agitated Dispersions

A rational theoretical treatment of the dynamics of drop breakup and drop coalescence in a turbulent agitated dispersion requires a fundamental knowledge of the behavior of the flow field. Accordingly, in this section, an introduction to turbulence phenomena and isotropic turbulent behavior is presented with recent pertinent findings included. Studies on the actual 

A thorough treatment of turbulence is given in the work of Batchelor, Brodkey, and Hinze (B5, B15, H9). Most of the work on modeling dispersed phase dynamics such as coalescence and breakage is based on models developed from concepts of isotropic turbulence. It seems appropriate to review these concepts here. 

Tbrbulence is considered to be a somewhat random flow of eddies superimposed on the overall average flow. If U = iUj. -I- jI7 -I- kU is the instantaneous point velocity in space, expressed in terms of its scalar along the unit vectors i, j, k, it may be written as 

The equation of motion for the turbulent flow of an incompressible fluid is obtained from the Navier-Stokes equations by replacing the instantaneous values of each point quantity by the sum of the average and its fluctuating component, and time averaging. This results in the Reynolds equations for incompressible turbulent motion in which there are more unknowns than available equations. Therefore additional relations are needed to solve the equations. 

In isotropic turbulence there are no shearing stresses and no gradients of the mean velocity. 

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Flow field in agitated dispersions(laminar/transitional dispersions,turbulent dispersions)... 

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