hallo,
I need to simulate a passive stack, but this header is not implemented by the comis version I use;
so I'm trying with a duct and 2 duct fittings (a Cowl at the top and a grille at the base).
That means a distributed pressure loss and 2 concentrated pressure losses.
some questions about it:
- which is the meaning of Zeta coeff. in ducts?
isn't enought for comis to know diameter(1/2) and  Roughness for friction coeff. calculation?
- how can I apply the duct fittings to the duct? or put these air flow elements in serie?
- can I have more informations about duct fittings and their parameters?

I hope somebody can help me,
thank you for your patience!

marco massetti,
politecnico di torino