The most common type of Non-NewtonianA non-Newtonian fluid is one that exhibits a viscosity that varies as a function of the applied shear rate or shear stress.non-Newtonian behavior is shear thinning or pseudoplastic flow, where the fluid viscosity decreases with increasing shear.
At low enough shear rates, shear thinning fluids will show a constant viscosity value, η0, termed the zero-shear viscosity or zero- shear viscosity plateau. At a critical shear rate or shear StressStress is defined as a level of force applied on a sample with a well-defined cross section. (Stress = force/area). Samples having a circular or rectangular cross section can be compressed or stretched. Elastic materials like rubber can be stretched up to 5 to 10 times their original length.stress, a large drop in viscosity is observed which signifies the beginning of the shear thinning region. At very high shear rates, a second constant viscosity plateau is observed, called the infinite shear viscosity plateau. This is given the symbol η∞and can be several orders of magnitude lower than η0depending on the degree of shear thinning.