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# Shear rate

Shear rate is a measure of the rate of shear deformation:

### Additional recommended knowledge

$\dot \gamma_{xy}=\frac {\partial v_x} {\partial y} + \frac{\partial v_y} {\partial x}$

For the simple shear case, it is just a gradient of velocity in a flowing material. The SI unit of measurement for shear rate is sec-1, expressed as "reciprocal seconds" or "inverse seconds."[1]

For a Newtonian fluid wall Shear stress (τw) can be related to shear rate by $\tau_{w} = {\dot \gamma_{x} \mu}$, where μ is the Viscosity of the fluid.

## References

1. ^ Brookfield Engineering - Glossary section on Viscosity Terms. Retrieved on 2007-06-10.