 Shear rate

The shear rate is the scalar rate at which adjacent material layers acquire shear strain. In simple shear $u_x=u_x(y)$, its signed value is $\dot{\gamma }=d{u}_x/dy$.

Shear rate is a measure of the rate at which one layer of a fluid moves in relation to another layer. It is a critical concept in fluid dynamics and rheology, particularly for non-Newtonian fluids, where the viscosity (resistance to flow) can vary with shear rate. Mathematically, shear rate (\( \dot{\gamma} \)) is defined as the change in velocity (speed) of a fluid layer divided by the distance between the layers.