Convective Nonlinearity in Non-Newtonian Fluids
  In the limit of infinite yield time for stresses, the hydrodynamic equations for viscoelastic, Non-Newtonian liquids such as polymer melts must reduce to that for solids. This piece of information suffices to uniquely determine the nonlinear convective derivative, an ongoing point of contention in the rheology literature. 
Hubert Temmen, Harald Pleiner, Mario Liu and Helmut R. Brand