Generalized Newtonian fluid

A generalized Newtonian fluid is an idealized fluid for which the shear stress is a function of shear rate at the particular time, but not dependent upon the history of deformation. Despite this type of fluid is non-Newtonian (i.e. non-linear) in nature, its constitutive equation is a generalised form of the Newtonian fluid. Generalised Newtonian fluids satisfy the following rheological equation:

where ${\displaystyle \tau }$ is the shear stress, and ${\displaystyle {\dot {\gamma }}}$ the shear rate. The quantity ${\displaystyle \mu _{\operatorname {eff} }}$ represents an apparent or effective viscosity as a function of the shear rate.

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