This paper summarizes some of the research into the effect of polymer additives on turbulent shear flow, which was conducted at the University of Liverpool between October, 1964, and October, 1966. The paper contains a brief description of the research together with a summary of the principal results and conclusions. The present work was devoted to a detailed examination of the mechanism of a particular flow by gathering information on friction drag, velocity distribution, concentration distribution, and correlation with Reynolds number and polymer concentration level. The particular flow chosen was the fully developed turbulent flow in a 2-in-dia pipe of Polyox WSR-301 solutions. A maximum drag reduction of 71 percent was obtained at a Reynolds number of 1.5 × 105 for solutions having polymer concentration of 10 weight parts per million. The drag reduction effect occurred only above some “critical” Reynolds number which was independent of concentration. The polymer additives were found to influence the flow in the neighborhood of a solid boundary. In this zone of the flow, the eddy viscosity was found to be much lower than that of water. In the absence of a boundary, as in free jet flow, the polymer additives had no effect on the flow characteristics. The experiments showed for the first time that the polymer molecules were uniformly distributed across the pipe diameter under all turbulent flow conditions investigated. A method of determining polymer concentration was devised for this purpose.
Visualization of Turbulent Flow Field with Fluorescently Labeled Polymer Additives by Simultaneous PIV/LIF Measurement and Investigation of Drag Reduction Mechanism
