Power-law fluid

A non-Newtonian fluid whose shear stress varies as a power of its shear rate. Its constitutive model uses a consistency index and a flow-behavior index.

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Power-law model: A constitutive equation that relates shear stress to shear rate through a consistency index and a power exponent. It is the equation used to represent this fluid’s shear-dependent viscosity.
Shear rate: A measure of how rapidly adjacent fluid layers move relative to one another. It is the independent variable in the power-law stress relation.
Rheology: The study of how materials deform and flow under applied forces. Power-law fluids are a standard model in rheological descriptions of flow.
Bingham plastic: A yield-stress material that flows linearly with stress only after a threshold stress is exceeded. Unlike the power-law model, it represents a finite stress required to initiate flow.
Shear-thinning: A decrease in apparent viscosity as shear rate increases. It occurs when the power-law flow-behavior index is below one.
Shear stress: The tangential force per unit area transmitted between neighboring layers of material. The model predicts shear stress from the imposed shear rate.
Blood rheology: The study of blood’s deformation and flow, including its dependence on shear conditions. Power-law models can approximate blood’s non-Newtonian flow over limited ranges.
Herschel–Bulkley model: A yield-stress constitutive model combining a threshold stress with a power-law flow term. It extends power-law behavior to materials that do not flow below a yield stress.
Shear-thickening: An increase in apparent viscosity as shear rate increases. It occurs when the power-law flow-behavior index is above one.
Dynamic viscosity: A measure of a fluid’s resistance to deformation under shear. Its constant value characterizes Newtonian flow, unlike most power-law behavior.