Degradation of flow drag reduction with polymer additives — A new molecular view

Abstract

This communication reports important new findings on the mechanism of the degradation of flow drag reduction with polymer additives from a molecular view. We first examine a critical assumption proposed by Brostow in analyzing the drag reduction and degradation of the drag-reducing polymers. Experimental results show that this assumption is not always correct, mainly due to the aggregation in the polymer solution. Theoretical analysis and experimental data are then used to show that the molecular weight distribution becomes narrower in a dilute solution but remains the same in a semi-dilute solution. Finally, an aggregate degradation mechanism is proposed for drag-reducing polymers in the turbulent flow.