Viscosity of some fluids may change according to the shear stress applied. These types of fluids are called “Non-newtonian fluids”. Non-newtonian fluids exhibit shear- thinning (Pseudoplastic), shear-thickening (Dilatant) or plastic flow behaviours.
See Also
Shear thinning fluids,
Shear thickening fluids,
thixotropy