Elongational Viscosity and Stability of Rotating Couette Flow

Abstract

A linear stability problem for Couette flow between rotating concentric cylinders of a dilute polymer solution which exhibits reduction of turbulent friction drag is examined. The effect of the addition of polymers on the flow is considered by an elongational viscosity which is assumed constant. It is assumed that the gap is narrow and that both cylinders rotate at almost equal speed in the same direction. It is found that the critical Taylor number increases from the value for the Newtonian liquid and that the corresponding wave number reduces.