Hello, and welcome to the forum:
I have looked at your file, and found no major problems.
Your “leak rate” is very low, and looking at the pressure profiles along the two facets it is clear that there is no noticeable effect caused by the extremely small leak rate you have.
The “artificial” leaks are caused by the way some facets are defined: Molflow+ establishes the orientation of a facet by taking the vector product of the vector connecting the first vertex in the facet definition time the vector connecting the second vertex to the third vertex.
If you look carefully, the STL CAD model has been “collapsed” but it has left all facets defining the “oblique” arm of the model (where all leaks take place, almost in the middle of it) defined as triangle. There are several couples of neighboring facets which are defined in a way that one has its vertex 1 and 2 along one of the two long sides of the triangle, while the other facet has vertex 1 and 2 along the much shorter side of the facet. This, I believe, creates a problem of tolerance in the definition of the HIT on a facet, and creates the leaks.It’s a problem of most geometries where facets are triangular with triangles having one side which is much shorter of the other two, like in your case. It is not a systematic problem, though, sometimes it doesn’t show up.
I simply selected some, 4 or 5 can’t remember, couples of these neighboring triangular facets as described above and used the Ctrl-H command /Menu “Facets”, “Shift indices” command) which permutates the vertices in the facet definition 1, 2, 3 become 2, 3, 1. I have then run the model for 700 M hits total, with zero leaks, compared to your 127 leaks for a running time ~5 times longer, I should have gotten 127/5 leaks, statistically, had my facet redefinition not had an effect).
Summarizing: for a fraction of leaks that you have, you can confidently use the result as “good”. Always look at the pressure profile: if a leak is really present then you’d see the effect on the pressure profile near that location, as a sudden drop of pressure, unphysical.
I include two screenshots of the model, yours and the one with the modified facets… see facet 59 and 60, neighbours, I did CTRL-H twice on number 60, and no leaks anymore at the interface between the two (one long edge).
Hope it is clear what I mean, if not write back.
Good luck.
