Hi,

I got to model Ma=4 flow over a missile. How big should I select the domain? If I cut the domain at the end of the missile and place pressure outlet, will it extrapolate from the interior? Or does it have to be far away from the tail. Also any comments on the distance of the inlet boundary from the nose will be appreciated.

Thanks in advance

baned

Hi!

I actually have no expirience with supersonic simulation - I hope this helps... You should use a domain with boundaries far away from the missle. Far enough that they won't significantly influence your simulation, but not too far since you don't wont it to calculate too long. the boundaries should be at least a few lengths of missle away from it. If you simulate an unsteady case you need to work with nonreflecting boundary conditions to ommit pressure wave reflection.

Hope this helps...

REGARDS

MATEUS

hi,

The distance ahead of the model does not have any influence if the free stream conditions are supersonic, as any pressure signlas from the nose of the missile will not propogate upstream in a supersonic free stream. Typically a distance of 2 diameters from the leading edge of the missle for an axiysmmetric case will work fine. The outlet boundaries in fluent if defined as a pressure outlet will extrapolate the variable values from the interior for supersonic flow while maintianing any set pressure for subsonic flow regions over the outlet. Unlike other commercial codes, fluent can handle mixed subsonic and supersonic outflows. Hope this is of help

Regards Nandu

Thanks, your comments will help a lot, I will try them.

Regards

baned

[rahuljws]

Originally Posted by Nandu
;108956

hi,

The distance ahead of the model does not have any influence if the free stream conditions are supersonic, as any pressure signlas from the nose of the missile will not propogate upstream in a supersonic free stream. Typically a distance of 2 diameters from the leading edge of the missle for an axiysmmetric case will work fine. The outlet boundaries in fluent if defined as a pressure outlet will extrapolate the variable values from the interior for supersonic flow while maintianing any set pressure for subsonic flow regions over the outlet. Unlike other commercial codes, fluent can handle mixed subsonic and supersonic outflows. Hope this is of help

Regards Nandu

will 2 times dia will not be very small?