Why a model with ducts fails in meshing or solving: overlapping extensions, isolated volumes, and units sitting on the floor, with the fixes.
This video reviews a model with ducts that fails to mesh, and fixes it step by step. When a duct is present, the mesher goes straight to its fourth attempt, with less automatic clean-up, so small gaps and misalignments are the user’s responsibility.
What the video shows
- The error message says the outlet on the computer room air conditioner (CRAC) must sit on the cabinet boundary.
- Cause: connecting ducts are used while the unit’s plenum extension is also on. Disconnect the ducts in the duct designer, turn the extension off in the geometry tab (toggle it if needed), then reconnect the ducts.
- Second problem: an upflow system in a raised floor room with a ceiling plenum. The sealed subfloor and ceiling are isolated volumes, because no air crosses them.
- Fix without changing the room type: add one small cable grill in the floor and one small ceiling grill.
- Third problem: units sitting at a Y start of zero with nowhere to draw air in. Lift them using the right-click align to Y min.
Tips
- Isolated volumes are named as one of the main reasons models fail in solve, because pressure cannot be calculated across a sealed surface.
- Use a non-raised floor room without a ceiling plenum when that is the real design.