https://doi.org/10.1351/goldbook.S05676
An idealized treatment of a fluid between two large parallel plates (to permit ignoring edge effects) of area \(A\), separated by a distance \(h\). If one plate moves relative to the other with a constant velocity \(V\), requiring a force \(F\) acting in the direction of movement, and the density, pressure, and @[email protected] throughout the fluid are constant, the Newtonian equation can be coupled with the equations of motion and of continuity to show that the velocity @[email protected] in the fluid is constant (= \(\frac{V}{h}\)), and that \(\frac{F}{A} = \frac{\eta \ V}{h}\). This idealized case (simple shear) is sometimes used to define @[email protected]