Drag reduction in rotational viscoelastic boundary layer flows

Abstract

Although the theoretical interpretations of the phenomenon of drag reduction, under turbulent flow conditions, caused by the addition of small amounts of high molecular weight polymers have not been exactly agreed on, it seems that drag reduction occurs on account of some interaction of turbulence and elasticity. Unfortunately, the best advantages of drag reduction are obtained with very dilute polymer solutions (concentrations of a few p.p.m.), and at higher concentrations these advantages seem to be rather minimal. Further, the attainment of turbulence under practical conditions is particularly difficult with more concentrated polymer solutions because of their high consistencies. It is thus of importance to investigate regions where reduction in friction could be obtained even under laminar flow conditions.