Problem with rotational perodicity
 

Hello,

I try to simulate the heat flow of a rotating disc.

Therefore I set up my mesh and BCs as followed:

-Simulation of a piece of 30°
-Rotational periodicity
-Laminar flow with Total Energy model
-Constant property gas: Air at 25°
-Inflow (top of 3d domain): Opening (Entrainment, static pressure set)
-Outflow (surface in radial direction): Outlet (static pressure)
-Disc: No slip wall with angular velocity
-Ma_max=0.8

I obtained a good quality hybrid mesh (quality>0.5, mesh expansion factor<12) but my CFX run (RMS residual criteria<e-06) shows some strange behavior of the wall heat flux (see attached picture):

1.) The heat flux shows no symmetry
2.) Near the rotational periodicity the heat flux increases on the one side and decreases on the other
3.) The heat flux decreases near the outlet.

I already tried some denser surface mesh at the disc but this didn't help.

Do you have any idea or advice which parameter should be considered more closely or what should be taken care of in the mesher (ICEM CFD).

Best regards

Which version of CFX are you using?

CFX v14.0 build 2011.10.10-22.59

Are you sure your simulation is properly converged?

Speckly heat flux like this can suggest that the mesh quality is inadequate. Getting good results for heat transfer is more difficult than for the continuity and momentum equations, so you may well need improved mesh quality and refinement for wall heat transfer.