SPH and walls - bugfix

Hello all, hi Moritz!

Because of the forum threat SPH and walls you find attached my input script.

@Moritz: Two mistakes were in your input script:

• Regions may not overlap in areas, which should be treated as walls.
• In your case the union-command creates additional convex corners, which are not calculated accurately.

I inserted also comments to my modifications.

I modified your script only for bug fixing. I did not check any physical properties (viscosity,...), time step, ...
It's working, but the results will probably be unrealistic.

Cheers,
Andreas