[OisinOC]

Hi,

I am trying to use rhoPimpleFoam to simulate airflow through some small ducts. I have 3D printed and measured the pressure drop for a square 90 degree bend, a round 90 degree bend and now a plenum like bend in the duct. My round bend had a good match for pressure drop and the square was reasonable but the plenum model seems very unstable when I view the residuals.



I think the problem might be that because the air spreads out as it enters the plenum and slows down there a wider range of velocities and my model is not set up correctly to handle it.

I've attached the case files but the mesh is too big to attach. Can anyone suggest how I might improve it?