[n936an]

Hello there,

This is my first time using snappyHexMesh with a custom STL file. It's the right wing of a 737.

After running blockMesh and surfaceFeatures, I ran snappyHexMesh (with only addLayers turned off). It seems to snap to the wing geometry just fine, but at the same time it randomly cuts some of the cells on the outermost faces of the blockMesh, which seem to be completely isolated regions from the wing itself. I've attached a screenshot highlighting the issue.

So far I've been trying to fix this in the CAD software, thinking it's got something to do with the STL file itself. I tried repairing the STL and removing some of the smaller details like the vortex generators, but I didn't see clear changes when rerunning snappy. I'm not sure if the issue is correlated to that.

So, my questions are:

1) Is this something I can fix using any of the dict files? Or is it a purely STL problem?

2) Would this affect how long the simulation takes (due to added number of cells) and/or the results?

I've also attached my case directory with the mesh in question.
https://drive.google.com/file/d/12o7...usp=drive_link

Thanks in advance for the help.

[rocketLauncher]

Hello,

Fixing the stl file is always a good instinct, try to refine the geometry stl mesh as best as you can. Are you using Salome for that?

Next step is the blockMesh. You appear to be using a very large domain, is that necessary? The quality of your castellation and snapping is closely correlated to the blockMesh. Aim for an aspect ratio of 1. To make things easier, you can use an interface like BaramMesh (it's free).

Then, check in the castellation parameters your feature angle. Default is typically 30, you could try lowering it a little.

Fianlly, in the snapping controls, you can increase the snapping relaxation iterations to 300 for a better quality. It will just take more time.

Try those and come back to the forum with some more screenshots if the problem persists. Good luck!