Rate of Strain and Flow

The terms rate of strain, velocity gradient and shear rate are all used synonymously and Newton s dot is normally used to indicate the differential operator with respect to time. For large gaps the rate of strain will vary across the gap and so we should write 

When the plot of shear stress versus shear rate is linear, the liquid behaviour is simple and the liquid is Newtonian2 with the coefficient of viscosity, rj, being the proportionality constant. 

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