AirFlowPad is a virtual 2D wind tunnel. Basically you draw the object, change the wind velocity and follow the calculation live on the screen.
After several seconds you see the final pressure and velocity
distribution. You can add parts to the object and remove them again to understand the influence of little changes to the air flow.
Internally the Euler equation is solved in the Lax-Friedrichs Scheme. For numerical stability this scheme adds an artificial diffusion term, which adds small calculation artefacts.
Have fun playing with aerodynamics.