Global rotating/ Rotating walls-Differente results

Hello,

         I'm modeling a rotating coupling contained in a stationary guard. This is a closed system, no inlet, no oulet, just air in the guard. I want to see at which temperature the air will arrive because of the rotating coupling.

         If I understand well, for my case, to model a rotating component, there are two ways:

          1. Select 'global rotating' in the wizard, and then in the boudary condition, define the guard as a stationary wall.

          2. Select nothing in the wizard, and then in the bondary conditions, define the coupling as a rotating wall

        Normally, I should obtain the same results. But the problem is that, the results I obtained is totally different. I want to know if there is someting wrong with my understanding?

        Thank you in advance for answering me.

Linxi

SolidworksSimulation