A general correlation for turbulent velocity profiles of dilute polymer solutions

Abstract

Dilute polymer solutions of sufficiently high molecular weight generally exhibit the phenomenon of drag reduction in turbulent flows. This has been usually studied by conducting either pressure drop/flow rate measurements or axial velocity profile measurements.

A general correlation, based on Prandtl's mixing length model of the form,

is developed herein to correlate the velocity data obtained in a 9 mm glass tube using an LDA system. This new correlation can be used to describe the velocity data of dilute solutions of polyacrylamide, xanthan gum and polyethylene oxide. The parameters α, β and Γ are unique functions of u ^*/〈ū〉 and are independent of polymer type, concentration, mechanical degradation and Reynolds number. Good agreement between two independent data sets and predictions of the velocity profile using the above correlation was observed.