Summary: J. Non-Newtonian Fluid Mech. 96 (2001) 405425
On two distinct types of drag-reducing fluids, diameter
scaling, and turbulent profiles
K. Gasljevic, G. Aguilar, E.F. Matthys
Department of Mechanical and Environmental Engineering, University of California at Santa Barbara,
Santa Barbara, CA 93106, USA
Received 29 October 1999; received in revised form 17 August 2000
Two distinct scaling procedures were found to predict the diameter effect for different types of drag-reducing
fluids. The first one, which correlates the relative drag reduction (DR) with flow bulk velocity (V), appears applicable
but the drag reduction versus V scaling procedure was successfully tested here for some surfactant solutions as well.
This feature, together with our temperature profile measurements, suggest that these surfactant solutions may also
show this type of 3-layers velocity profiles (3L-type fluids).
The second scaling procedure is based on a correlation of w versus V, which is found to be applicable to some
surfactant solutions but appears to be applicable to some polymer solutions as well. The distinction between the
two procedures is therefore not simply one between polymer and surfactants. It was also seen that the w versus
V correlation applies to fluids which show a stronger diameter effect than those scaling with the other procedure.
Moreover, for fluids that scale according to the w versus V procedure, the drag-reducing effects extend throughout
the whole pipe cross section even at conditions close to the onset of drag reduction, in contrast to the behavior of