Consider the flow through a two-dimensional box with staggered inlet and outlet as show in the figure below:
The flow enters and exits the box with a uniform speed
. The aspect ratio of the box is
The Demonstration plots the streamlines for this potential flow for a user-set value of
These streamlines are the solution of the equation
subject to the boundary conditions:
The solution methodology is based on Chebyshev orthogonal collocation with
This problem also admits an analytical solution given by T. Bennett :
. We have found excellent agreement between our numerical solution and the analytical solution.
 T. Bennett, Transport by Advection and Diffusion
, New York: Wiley, 2012.