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Definition of the shear rate:

Equation 2.2

γ ̇ = v/h

γ ̇ (pronounced: gamma-dot); with the velocity v [m/s] and the distance h [m] between the plates, see Figure 2.1.

The unit of the shear rate is [1/s] or [s -1 ], called “reciprocal seconds”.

Sometimes, the following terms are used as synonyms: strain rate , rate of deformation, shear gradient , velocity gradient .

Previously, the symbol D was often taken instead of γ ̇ . Nowadays, almost all current standards are recommending the use of γ ̇ (see e. g. ISO 3219-1, ASTM D4092). Table 2.1 presents typical shear rate values occurring in industrial practice.

For “Mr. and Ms. Cleverly”