MRF size - weird flow pattern
 

Hi all,

I am trying to validate an existing fan. The results are reasonable (regarding volume flow rate) but when inspecting the flow pattern, I oberserved non-physical behaviour in the transition from the MRF-zone to the "normal" mesh zones.

The behaviour is also persistent with a smaller MRF, but less pronounced.

Here is sketch of my case:
Attachment 90036

And the weird flow behaviour is shown here:
Attachment 90037


Is there any explanation for this? And how to avoid it?


Best wishes