This page has links to MATLAB code and documentation for the finite volume solution to the one-dimensional equation for fully-developed flow in a round pipe
where is the axial velocity, is the pressure, is the viscosity and is the radial coordinate. This is a simple and well-known flow with the exact solution
where is the pipe radius.
The utility of this code archive is that it shows how to derive the finite-volume model in radial coordinates. The model code also gives an example of how mesh refinement improves the accuracy of the numerical model.