Introduction - If you have any usage issues, please Google them yourself
The 2D CFD Program NaSt2D
The program is a 2D solver for the incompressible, transient Navier-Stokes equations including the temperature equation and free boundary problems. It uses finite differences for discretization on a structured equidistant staggered grid, central and upwind (donor-cell) discretization of the convective parts and an explicit time stepping scheme. The free boundary value problems are treated with the MAC technique.