The velocity profile in fully developed laminar flow in a pipe of diameter $$D$$ is given by $$u = {u_0}\left( {1 - 4{r^2}/{D^2}} \right),$$ where $$r$$ is the radial distance from the center. If the viscosity of the fluid is $$\mu ,$$ the pressure drop across a length $$L$$ of the pipe is

For laminar flow through a long pipe, the pressure drop per unit length increases.

The discharge in $${m^3}/s$$ for laminar flow through a pipe of diameter $$0.04$$ $$m$$ having a centre line velocity of $$1.5$$ $$m/s$$ is: