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CAD clean up for CFD simulation
arshia_zarrin
Member Posts: 2 ✭
Hello!
I'm working on a CFD simulation for a small pump impeller using SimScale (first image). The platform’s integration with Onshape makes it convenient to import my geometries directly. However, I’m encountering some challenges with CAD cleanup before meshing, and I’d appreciate any insights.
- Outlet Geometry Issue – The outlet features multiple surfaces that cause a high concentration of small mesh cells where they meet (second image). I've been trying to merge these faces but haven't been successful. Does anyone have recommendations on how to simplify or clean up this region?
- Housing-Volute Interface Issue – There is a very thin and elongated edge where the housing meets the volute, leading to highly non-orthogonal mesh elements (third image). I’m struggling to find a good way to clean this up—any suggestions on how to improve the geometry for better meshing?
Any advice would be greatly appreciated!
0
Answers
Do you have any specific questions related to Onshape? For example I don't see anything wrong with the outlet geometry in Onshape, except that there are no fillets and the transition is sharp. And the volute interface, I see that there is a fillet smoothing where the volute meets the entrance / outlet, but I don't see anything wrong with it. What specifically (In the part studio) are you trying to do to those regions.
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I've used simscale a lot without geometry issues but I have a process. Simplify the model and get it working. Then add a little complexity and remesh.
-take the fillet out, mesh it again and get it to work.
-then add a fillet and use mesh control to dial in a working mesh.
The knife edge that's peeling the flow off needs to be sharp as possible and modeling the flow separation in that zone will require mesh refinement. At this point, I think you'll be chasing your tail and it'll never converge on something exact.
It's really difficult to fix a model that won't mesh. It's far easier to simplify the model, mesh and then add complexity.
I'm assuming you built the geometry.
From the mesh, you can see it doesn't like the vertices where the surfaces are coming together. Turn off adaptive meshing and tell the mesher you're not interested in those details. Where you're peeling the water off, jack that mesh up in that area.
Are you using rotating frames? How are you spinning the fluid?