Hey there,
It’s Robin from CFD Engine & this email didn’t quite turn out as planned.
It was meant to be email about how to wrap geometry using a secret feature in snappyHexMesh but, after several attempts, I gave up.
So this is a reminder that some things are much harder than you first thought & that some things probably aren’t worth the effort 🙈
I’ve also got a favour to ask, but first here’s how the “wrapping” went down…
-surfaceSimplify
I’m always on the lookout for ways to make my meshing process a little better. In particular I’d like a robust way to wrap complex-but-not-that-important geometry.
You know the kind of thing, assemblies that need a lot of work to clean-up, that are too important to ignore, but that wouldn’t hurt the results if they were a little less detailed.
I’ve had some success wrapping geometry in MeshLab, but it could be better.
So when I spotted that -surfaceSimplify in snappyHexMesh might do a bit of wrapping, I had to take a look. There’s no documentation, but surely I could figure it out?
Turns out, I couldn’t.
foamyHexMesh
Not only is it possibly the least used feature of snappyhexMesh, it isn’t really a snappyHexMesh feature at all. The first warning sign (& one I shouldn’t have ignored) came when it asked for a foamyHexMeshDict 👀
In case you don’t know, foamyHexMesh is the promising-yet-unloved younger brother of snappyHexMesh. It uses a different method to generate its cells, should handle feature edges nicely, but it needs a watertight input geometry.
I’m pretty confident using snappyHexMesh, but I’m waaay out of my depth with foamyHexMesh – time to fire up the tutorials and see what’s what.
And what did I find? Long dictionaries, with many curiously-named settings that do who knows what, coupled with an an opaque process that feels half-finished & a propensity to crash without much explanation.
Now know what it must feel like to be snappyHexMesh newbie 😳 a humbling experience that should help me to make better content in the future.
In the meantime, I’ll go back to wrapping in MeshLab and continue giving foamyHexMess a wide berth.
How do I…?
Speaking of future content, I’ve got a small favour to ask you.
I’m collecting questions for a new side project – atomic nuggets of OpenFOAM trivia to help you do something specific – things like…
- “How do I calculate total pressure coefficient?”
- “How do I plot residuals?”
- “How do I change a patch name?”
Here’s the favour – could you think back to when you last asked a question like that & share it with me?
No context or explanation required.
A single sentence, starting with “How do I…?” that relates to achieving a specific goal in OpenFOAM would be perfect.
“How do I use snappyHexMesh -surfaceSimplify?” is already on the list 😉 but I’m intrigued to see what else you might add.
The idea is to collect at least 100 of these questions, pair them with their answers & create the beginnings of a useful resource for OpenFOAM-ers.
Here’s the link to leave your question & here’s hoping you can help 🙏
Until next week, stay safe
