Algebraic turbulence model for EPR

It makes clear after the experimental experience that two Reynolds numbers (3.30) should be responsible for the turbulence in EPRs, global and local ones, correspondingly  

The first one is defined by the characteristic length H (the width of a duct or the height of the EPR h) and the velocity (the mean velocity in a duct or the undisturbed boundary layer velocity Uco) and should determine the stability of the flow as a whole. The second one is defined by the dimension of an individual obstruction 2r and the local flow velocity around it U. Just the local Re determines the vortices shedding from the obstruction. It is known [304] that 

The working range of the local Reynolds number can be estimated as 1000 Re 30000, so the vortices behind individual obstructions are still ordered with only 

Over the EPR all their works postulated the logarithmic mean flow distribution (1.1) with a roughness coefficient z0 to be determined empirically. Several relations were suggested for the latter [155]  

Another formulas tried to represent the density of a forest  

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