define a porous surface with solid material on it in Gambit
 

Dear All;
I am working on CFD of a tray dryer. I want to know, how can I make each tray (a porous surface with solid material on it) and mesh them? Do you have any articles or tutorials about it? How can I contour each tray by Gambit program? I do appreciate if you kindly answer and help me.
Best regards

Sami