Hello every one. can any one please tell me, how to modify the properties of the air so that it idealizes to vaccum, Wat should be the density, thermal conductivity and other parameters, I need to modify the properties of air because I am solving a radiation problem and need to have vaccum in some zone.

thanks ashish

Although I may not be able to help you set radiation problem I would just like mention a couple of things which may help you think towards the solution you are desiring. Vacuum is measured as the absolute pressure below atmospheric pressure. This absolute pressure (below atm) when input as operating condition will denote desired vacuum. Air properties can anyway be changed as desired in materials panel. If vacuum is desired only in one of the zones, the desired value of absolute pressure can be patched in that zone alone.

Hi!

Prasad is right, additionally I wolud suggest, to use as air material properties for density the "ideal gas". Otherwise, changing operating pressure will have no effet!

Ralf