Nonlinear fluid behavior: from shear thinning to shear thickening

A phenomenological model is introduced which describes both shear thinning and shear thickening behavior. Consequences of this model are presented for plane Couette (simple shear) flow. The non-Newtonian viscosity and normal pressure differences are discussed for a stationary situation. The dynamic behavior - stress growth and relaxation - is analyzed. A stress hysteresis is found in the shear thickening regime. The model is also applied to the vorticity free planar (biaxial) deformational and (uniaxial) elongational flow geometries.