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[snappyHexMesh] Airfoil trailing edge boundary layer refinement with snappyHexMesh

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Old   February 20, 2024, 05:35
Default Airfoil trailing edge boundary layer refinement with snappyHexMesh
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Tommy Nee
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Hi

I'm looking to further refine my mesh around the trailing edge of an airfoil for a mesh with snappyHexMesh. I have so far refined the very near wall layers to a level that I am happy with. What I want to try to improve is to have less layers towards the trailing edge so that the extra refinement I have defined in the castellation process is no undone by the last layers. I know I could reduce the number of layers but then there is too great of a jump in size elsewhere along the airfoil.

I'm currently using two snappyHexMeshDict files, one for castellation and snapping and another for adding layers with the quality controls turned off. I have also tried defining different regions based on where I want less/more layers but this has not worked. The images attached are of what my mesh looks like right now and what I'd like it to look like (roughly).

mesh_TE.png mesh_TE_wanted.png

If anyone has any tips for this I'd love to know! Thanks!
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Old   February 20, 2024, 05:57
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I realise I should probably have uploaded my snappyHexMeshDict files too, sorry!

snappyHexMeshDicts.zip
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Old   February 21, 2024, 03:27
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Hey,


Maybe you could split the airfoil in several patches and set a different number of layers for each?


Out of curiosity, what does checkMesh give you after the layer addition? Your mesh looks ok-ish, but having no quality control must be tough if it works though, I will shamelessly steal your dicts!


Edit: I saw that you already tried to have different regions for the airfoil, my mistake!
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Old   February 21, 2024, 13:17
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Hi,

Thanks for the response! I figured out my issue was that I was trying to define two exactly overlapping patches so Openfoam didn't really know what to do and gave some faces to one patch and some to another, so yes I divided each patch up individually as separate stls and now i have stepped layers like I was looking for (although it's a pain for outputting the pressure on each individual sureface!)

In answer to your mesh quality question, I believe for the above airfoil the only failure on checkMesh was high aspect ratio, which I'm okay with as I have to resolve the boundary layer to y+<=1 and don't have the computational power to have nice aspect ratios near the wall!

Thanks again
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addlayercontrols, snappyhexmesh, trailing edge, viscous layers

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