Rheology: An Historical Perspective

Abstract

This chapter discusses some distinctive rheological concepts and phenomena. The governing equations for elastic liquids are far more complex than the Navier-Stokes equations and accordingly more non-dimensionless groups are required in rheology. At the simplest level, one might argue that the addition of a characteristic time A as an extra parameter would, at most, add one more dimensionless group to the problem, but the very complexity of the equations ensures that non-dimensionalization is not as straightforward as in the Newtonian case, arid only for the most restrictive of liquid types and flow regimes. The rod-climbing phenomenon is now generally referred to as the Weissenberg effect.