On the explanation and correlation of turbulent drag reduction in dilute macromolecular solutions

A simple mechanistic picture of turbulent drag reduction is proposed, based on the recent work of Corino and Brodkey for Newtonian fluids. Possible explanations are then considered from a phenomenological viewpoint, and the applicability of the well‐known dumbbell model toward this end is discussed. It is seen that the predictions of the “molecular” dumbbell model are surprisingly similar to those of the “continuum” convected Maxwell model utilized by Seyer and Metzner. Furthermore, the significance of the fluid relaxation time θ in characterizing the drag‐reducing effectiveness of a polymer solution is shown to follow from a number of qualitative arguments. A correlation is proposed, closely related to the recent correlations advanced by Rodriguez, Zakin, and Patterson, and Astarita, Greco, and Nicodemo. Some new aspects of this correlation are discussed.