boundary conditions for the sky?
 

Following on from my previous post, (5th year MEng CFD project)...

I'm just wondering how people have treated boundary conditions for the sky/open atmosphere in problems?

I was thinking about having a free-slip wall a large distance away from the area of attention with coarse meshing for the large volume above the area of attention.

I'd greatly appreciate peoples experiences/thoughts. Thanks.

Re: boundary conditions for the sky?
 

the real one is infinite outflow ...