Transient boundary conditions

Dave

Basically my geometry consists of a pressure inlet and 4 pressure outlets (representing the air intake system with intake ports on a four cylinder engine), but only 1 of the outlets is open at once, when that one closes, another opens. How do I model this in FLUENT, do I need a UDF and how would I go about writing a UDF to do this? Bear in mind that my programming skills are virtually nil! Any help would be greatly appreciated!!!

Thanks Dave