Straight, smooth or rough pipe without fittings

Straight, Smooth or Rough Pipes Without Fittings 

Already in a relatively early study, Evans [121] had concerned himself with the theoretical treatment of the diffusion process, according to which an injected dye is uniformly mixed in a turbulent pipe flow. He calculated the courses of the standardized concentration c/cg (cg is the average concentration after molecular mixing) over the standardized radius r/R for a uniform and for a parabolic distribution of diffusion coefficients and compared them with the measured concentration profiles at various distances along the mixing length 

First it was found, that the effect of the pipe roughness on the mixing length followed a law, which had already been established by Taylor [538]  

Im/D oc V Cf.smooth/Cf,rough (Cf - friction factor in pipe flow). 

The average turbulent Schmidt number (Scturb = D is the eddy dif- 

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