jeltson,
I might suggest you re-word your question. Are you looking to find out if Mechanica can calculate the load distribution given a fluid, in/out pressures and nozzle shape? Or, are you interested in finding out whether or not Mechanica can simply handle applying a pressure load, calculated by some CFD code or hand calculations, to the surface of the nozzle? If your answer is the first situation, then Mechanica cannot handle this as it does not perform any CFD analysis. Mechanica can apply pressures to analyze stresses and deflections in the nozzle.
I hope this helps,
Kaz