Interface impeller/volute
 

Hi,

I simulated a centrifugal fan (impeller + volute), using a frozen rotor interface.
In the results I can take two pressure values of at the interface, one for the rotor side, one for the volute side. It turn out that the value are differents (exemple: rotor side- 3729 Pa; volute side: 3483 Pa).
Is the difference normal?
Which value is more correct to use in the calculations?


Many thanks

The interface should have the same pressure at both sides. I suspect the difference you are seeing is due either not matching the same exact point, or interpolation errors. Note CFX uses a sophisticated finite element-like approach which includes evaluation at integration points which are at a finer pitch than the nodes. The results file just includes the nodal values and does not include the integration points. This means interpolation on the results file is not the same as interpolation on the full solver solution values.

many thanks