Apparent viscosity

This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Apparent viscosity" – news · newspapers · books · scholar · JSTOR (March 2009) (Learn how and when to remove this message)

In fluid mechanics, apparent viscosity (sometimes denoted η)^[1] is the shear stress applied to a fluid divided by the shear rate:

${\displaystyle \eta ={\frac {\tau }{\dot {\gamma }}}}$

For a Newtonian fluid, the apparent viscosity is constant, and equal to the Newtonian viscosity of the fluid, but for non-Newtonian fluids, the apparent viscosity depends on the shear rate. Apparent viscosity has the SI derived unit Pa·s (Pascal-second), but the centipoise is frequently used in practice: (1 mPa·s = 1 cP).