The effect of dilute polymer solution on the Strouhal frequency of circular cylinders.

Abstract

Flow of aqueous solutions of Polyox WSR-301, at a concentration of 25 wppm, was investigated in the cylinder drag transition region of Reynolds numbers. Frequency spectrum and drag force were measured on a circular cylinder (diameter 1 inch). Frequency spectrum, Strouhal frequency and drag force also were measured on circular cylinders in water (diameter 1 and 1-1/2 inch). The polymer additive did not alter the vortex shedding frequency from that of water at the same Reynolds numbers. As the polymer degrades, a state is reached where concentration, Reynolds number and body size combination become such that the transition occurs in the boundary layer. Transition in the polymer solution occurred earlier than that in the pure solvent. At one Reynolds number, several regimes of flow may be observed as the polymer solution degrades.