[b16328]

Hello,

I am simulating a propeller using MRF in OpenFOAM. The geometry is shown below and consists of one blade with cyclic axisymmetry to represent 5 blades. I generated my mesh with Pointwise and it consists of an inner MRF zone and a surrounding farfield that is stationary. The case converges well (to 1e-10 over 2000 iterations) and the flow field is generally believable, however the interface between the rotating and stationary zone looks incorrect on the radial MRF boundary and the accelerated flow in the MRF zone does not influence the surrounding farfield. The velocities are intentionally clipped in the renderings to more clearly show the strange behavior on the MRF zone boundary.

I have tried a variety of meshing approaches and settled on a long MRF zone that extends to the end of the domain as it helps show more of the rotation in the flow field by capturing the wake downstream. When using a short MRF zone, the wake is 'straightened’ immediately after the zone ends which seems wasteful as more of the mesh can be rotating to better resolve the wake.

I have also tried a variety of case setups including not explicitly defining the patches between the two zones, defining them with cyclic, and defining them with AMI. I have seen weird behavior such as mass not being conserved across this problematic interface and generally all the cases give the same visualization that I believe is not correct. In all of these cases, I have set all of the patches in the simulation apart from the blade and propeller hub as “nonRotatingPatches”.

What could be influencing the lack of communication between the MRF and farfield zones? I can post my case setup if that would be helpful.

Thank you in advance.

Setup.jpg

Propeller.jpg

Wake.jpg