Hi,
I'm importing files from SolidWorks, and my model is essentially a hollow pyramid shape. I want the flow to go from the large end of the pyramid to the smaller end. I noticed though that in order for the flow to resolve properly, the object has to be solid. If I model the object as it would be in a real life as a hollow pyramid, MolFlow just sends the flow through the thin walls of my model. Is there a way to make the flow go through "open" spaces?
Thanks,
SW
Hello.
It is very important to understand that Molflow doesn't see any volume, instead it only sees oriented surfaces, i.e. facets with normals vectors pointing in one direction.
You can display the normal direction by selecting a facet and enabling "Normals" in the upper right corner.
By default, in an STL file all surfaces are oriented towards the solid part.
In case of (default) 1-sided facets, Molflow desorbs molecules towards the normal vector side, and detects collisions only from the normal vector side. In case of 2-sided facets, molecules are desorbed to both directions and collisions are detected from both sides.
In case of a solid body, this ensures that molecules will by default be desorbed towards the interior, and remain there, as walls catch all rebounds (since they are oriented inwards).
I've created a hollow pyramid to show that by default molecules are desorbed in the walls:
However, you can swap the normal vector direction by selecting Facet / Swap normal from the menu, the shortcut is CTRL+N.
In that case, after changing the wall directions, molecules will remain in the inner volume:
However, you will use double the necessary facets, since your wall has a thickness, so I would still say it's a good practice to model the vacuum part as a solid.
Hope I helped, Marton
Marton,
Thank you very much, that is great help!
Stephen