**Shear rate** is the rate at which a

shear is applied.

## Simple Shear

The shear rate for a fluid flowing between two parallel plates, one moving at a constant speed and the other one stationary (

Couette_flow}, is defined by

<math> dot gamma = frac </math>

where

- <math>dotgamma</math> = The shear rate, measured in reciprocal seconds
- <math>v </math> = The velocity of the moving plate, measured in meters per second
- <math>h </math> = The distance between the two parallel plates, measured in meters

Or,<math>dot gamma_=frac + frac </math>

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<sup>-1</sup>, expressed as "reciprocal seconds" or "inverse seconds."

The shear rate at the inner wall of a

Newtonian fluid flowing within a pipeRon Darby,

*Chemical engineering fluid mechanics*, 2nd ed. CRC Press, 2001, is:

- <math> dot gamma = frac </math>

where:

- <math>dotgamma</math> = The shear rate, measured in reciprocal seconds.
- <math>v </math> = The linear fluid velocity.
- <math>d </math> = The inside diameter of the pipe.

The linear fluid velocity

*v* is related to the volumetric flow rate

*Q* by:

- <math>v = frac</math>

where A is the cross-sectional area of the pipe, which...

Read More