This model is used to fit viscosity data generated at low shear rates (where the power law model fails.)
with ho the Newtonian viscosity, k the consistency and n the power law index +1.
The Williamson model can be used with data generated at low shear rates (where the power law model fails).
For high shear rate data with an infinite viscosity plateau, the Sisko model should be used.
A more complex model describing Newtonian and infinite viscosity behavior is the Cross model.
