Weird simulation behavior, gas seems to be inside the geometry

hi all, I’m just getting started with molflow and i running into some issues. right now when i start a simulation the lines from the simulation to be inside the walls of my vacuum tube, rather than the internal cavity where it should be, an image is shown below. i think i might have an issue with my geometry. if you can give me any advice that would be greatly appreciated.

  1. The immediate cause is that the STL defines normals to point towards the solid part of the body. You need to do Facet menu → Swap normal on all facets. More info on normal vectors in Molflow: Documentation: Facet parameters | MolFlow+ and SynRad+ (see Sides section)
  2. We recommend to model the geometry inside out, that is, the vacuum part only as a solid: Designing geometries for Molflow - MolFlow+ / SynRad+ documentation
  3. If that’s too difficult, you can use the Smart Select to quickly remove the outer layer which is not hit by facets.