Steady Flow between Parallel Plates
$$ u(y) = \frac{U}{h} y - \frac{1}{2\mu} \frac{dp}{dx}\, y \,(h-y) $$ CaseParallelFlow
★ Volume flow rate per unit width of channel $$ q = \int_{0}^{h} u \, dy = \frac{U h}{2} \left[ 1 - \frac{h^2}{6 \mu U} \frac{dP}{dx} \right] $$ \(\rightarrow\) Average velocity $$ \bar{V} = \frac{q}{h} = \frac{1}{h} \int_{0}^{h} u \, dy = \frac{U}{2} \left[ 1 - \frac{h^2}{6 \mu U} \frac{dP}{dx} \right] $$
Special cases

Plane Couette flow $$ \frac{dP}{dx} = 0 \rightarrow u(y) = \frac{U y}{h} $$

PlaneCouetteFlow

Plane Poiseuille flow $$ U = 0 \rightarrow u(y) = -\frac{1}{2\mu} \frac{dP}{dx} \; y (h - y) $$

PlaneCouetteFlow