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Ansys Learning Forum › Forums › Discuss Simulation › Fluids › Natural convection convergence issues › Reply To: Natural convection convergence issues

May 7, 2024 at 10:21 am
Rob
Forum Moderator

Assuming the mesh quality is good, and with inflation over the holes it may not be (look up aspect ratio) then you need to have a look at operating density & boundary conditions. 

For incompressible ideal gas set the operating density to be equal to the outside condition: initialise from the boundary and let Fluent calculate the density. Set that exact value, to all decimal places, in the Operating Conditions panel. You're aiming to remove the density term in equation 7-68  https://ansyshelp.ansys.com/account/Secured?returnurl=/Views/Secured/corp/v241/en/flu_ug/flu_ug_bcs_sec_operating.html%23flu_ug_sec_hxfer_buoy

You may also want to patch in an updwards velocity in the chimney to assist the solver.Â