Reply To: Geometry preparation for CFD

[peteroznewman]

ArraynWhen you say extruded what exactly are you doing to the solid body? I think you mean adding or removing from the solid volume, but maybe you are doing something that I would call imprinting. It is very important to start the project with clean geometry.nOnce you use the Share button in SpaceClaim, you don't need any contacts. Delete them all. It is better to start a fresh Fluent model, because the old Fluent model will remember that there were contacts and you will waste time cleaning up the old model. It is much better to start a fresh Fluent model with clean geometry and no contacts.nHere is an idea to make getting started a bit easier. Do only the airflow in the room, not the room and ducts together. That means each diffuser is an Inlet and you will define the flow rate for each diffuser and it will flow straight into the room and out the outlets.nBut first, in a separate model, simulate just the flow of air inside one duct. Again, this will be a single solid simulation. The diffusers are Outlets in this model and the rectangular end at the root of the duct tree is the Inlet where you define the flow into the duct tree. The results of this model will be the flow rate out of each individual diffuser. You can then enter those values into the Room model for Inlet flow rate at each diffuser and this will be a good approximation of the combined flow model, but you will have two smaller models that are easier to mesh and faster to solve.nWhen meshing one duct, use an element size of 50 mm and use Inflation to capture the boundary layer. That will result in a mesh of 453k elements, which is under the 500k Student license limit. That element size will be too large for the Room, which has a much bigger volume to fill.nDrag and drop a Fluent analysis onto the Mesh cell and it will create a fresh Fluent model that should run. I set the Smoothing to High and the Quality on the Mesh Metric of Skewness has a Max value of 0.84 which is good enough to get some initial results.nGood luck! n