Theory of Concentration Dependence in Drag Reduction by Polymers and of the MDR asymptote

摘要

A simple model of the effect of polymer concentration on the amount of dragreduction in turbulence is presented, simulated and analyzed. The qualitativephase diagram of drag coefficient vs. Reynolds number (Re) is recaptured inthis model, including the theoretically elusive onset of drag reduction and theMaximum Drag Reduction (MDR) asymptote. The Re-dependent drag and the MDR areanalytically explained, and the dependence of the amount of drag on materialparameters is rationalized.