Alienware 17 R2: Bottom vents intake or exhaust?

Are the vents on the underside of the AW17 R2 for intake or exhuast?  I put the unit on its side and grabbed some toilet paper and dangled it next to the vents, but I guess the system wasn't being stressed so nothing happened.

Reason I want to know is that I want my cooling pad fan pushing air in the same direction the air goes through those vents (don't want the cooling pad blowing air into the vents if hot air is supposed to exhaust from there or vice versa).