SimScale CAE Forum

Enclosure volume not accurate surface against the part

I am new to CFD and having some difficulties learning Simscale for external flow hydrodynamics. My particular question here is about the enclosure and the accuracy of the interface with the part surface, which in this case is an airfoil Eppler E851. I have used the SimScale app to export the airfoil part from Fusion 360 to SimScale. This works fine and the part looks good after importing. (comes in as a Step file). After removing the shape from the enclosure using the CAD Delete function the Copy of the part with the enclosure becomes a Parasolid but the surface interface to the part lacks much detail and is a series of coarse flats, not a small splined airfoil surface. Whether I use a coarse mesh or refined mesh the same shape persists. I would expect this will affect the analysis as the shape of the airfoil is very critical. I wil try and paste some images here.
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My question is does this matter, and how can I get a better surface interface representing the airfoil shape.
Thankyou

Hi, this is Fillia :0 Could you provide a link to the project as well please?

Best regards,
Fillia

Sure here is the link.
https://www.simscale.com/workbench/?pid=7330161621765272955&mi=spec%3Acf250d06-1716-464e-b807-fbaf1836e70c%2Cservice%3ASIMULATION%2Cstrategy%3A3&ps=analysis%2FIncompressible--oneOf%2FboundaryConditions%2F3
This model does not have the fine mesh but shows the basic problem.
Thanks

I added a ‘Facet split’. Does it look better now? :slight_smile: Let me know!
https://www.simscale.com/workbench/?pid=2910621729580396&mi=geometry%3A24&mt=GEOMETRY

Thanks for that. I see it is a lot better now but I am still concerned about the leading edge smoothness. See image below.


The Fusion 360 smoothness is much better than the image.

I see, a workaround would be to create and import the Flow region from Fusion 360, what do you think?

Yes I thought that might be an option. I have not done that before so would I build a solid body of the enclosure, then remove the airfoil, and then the resulting body export to SimScale. Is that what you are suggesting?

I have tried 2 things:

  1. Generate the enclosure body in Fusion 360 and remove the airfoil section body.
  2. Generate a sketch in Fusion 360 of enclosure side view and airfoil and extruding it to required enclosure width which is also a body.
    Both methods show reasonable smoothness in Fusion 360 after zooming in and waiting for regeneration.
    However when importing into SimScale the result is still a coarse representation of the airfoil.
    I have seen examples in SimScale projects where the resulting airfoils have good smoothness so there must be a way to do this I think.
    Regards

I have forwarded this issue to my team, and will update you as soon as I have news :slight_smile:

I have found a work around. The problem seems to be the spline representation of the airfoil shape. So I regenerated the airfoil from 64 points to 200 points and imported into Fusion 360 as straight lines between the points. The shape is sufficiently smooth and reads into SimScale OK. See preliminary mesh -more refinement needed yet. One problem is each straight line generates a surface so I end up with lots and lots of surfaces but I can group them to define the airfoil surface. If you do find another way forward I would be interested but I think I can proceed now. Thanks for your help.

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