Need help with Grid Adaption

_stephen_

Good day,

I am modelling a room (10m x 5m x 5m) with air entering the domain through 6 15mm x 8000mm louvres in the ceiling at an angle of 45°. I mesh the room in gambit as good as possible but due to the big variations in scale the simulation results (especially the velocity in the domain) are unsatisfactory. Therefore I want to adapt the grid in Fluent and encountered several problems:

1) under what circumstances is the y+/y- Adaption Panel available - I tried quad and tetra cells; before and after iterations; sometimes the menu item is disabled

2) is it possible to coarsen 3d cells in Fluent at all? according to the manual (23.8.3) not really: "Note that if you are using hanging node adaption (the default), you will not be able to create a grid that is coarser than the original grid. For this, you must use conformal adaption. Note also that conformal coarsening is only available for 2D or axisymmetric geometries."

3) when I refine the grid with a y*/y+ adaption, the min and max values of y before and after refinement do not change, but several cells are reported to be refined

Any help would be greatly appreciated

Thank you -Stephen-