Thank you Don, but what I am trying to do is different:
I want to use the model optimization capabilities of CREO2.0 using the value (in my case the pressure gradient) calculated in Ansys CFX as the target parameter (I am trying to minimize it).
in that case CREO2 is driving the whole process, and from what I see the best way to do that is to make an "External Analysis" Feature which will execute Ansys input the new model dimensions, start the calculation, pick up the new pressure gradient value, and give it back to CREO....Easy to say I know...but If I had a good idea on the ways to use "External Analysis", at least I would know how hard it is to accomplish...