question
 

Hi guys,
who can answer this question?
I'm simulating a centrifugal fun. I use to monitor the flow rate at the outlet of the system. If I look, by means of the "solver manager" of CFX, the graph concerning the flow rate I see oscillations. If I increase the total pressure (almost equal to static cause the flow is slow in that part) at the outlet this signal is more stable until a certain value of the pressure where I don't see oscillations and the signal is suddently stable. How can I interpret this?

The fan might be off its design point with the initial point, and increasing the pressure pushes it closer to an ideal operating point where the flow is simpler. This makes convergence easier.