Relationship between drag reduction and flow structure in a Taylor–Couette flow with polymer solution

Abstract Polymer-induced drag reduction, commonly referred to as the Toms effect, has been extensively studied in wall-bounded turbulent flows such as pipe and channel flows. In contrast, fewer investigations have focused on rotating shear flows. In this study, we experimentally investigate the effect of polyethylene glycol (PEG), a water-soluble and non-toxic polymer, on turbulent Taylor–Couette flow, which develops between concentric cylinders where only the inner cylinder rotates. Torque meas