[cjc96]

Hello everyone,
In what seems to be a rite of passage for OpenFOAM and snappyHexMesh I am currently having an argument with prism layers.

I see a lot of problems relating to layers not fully covering sharp edges, but I've yet to find an example of my own problem, where the layers are seemingly pulling the initially well-snapped mesh away from the surface. I'm not really sure how best to explain it, so I've included a few images.

Here you can see the mesh without layer addition, with the cells well snapped to the surface of the .stl representing my domain. I know such a domain could be made using blockMesh, but I was experiencing some other issues using that method so am attempting this as an alternative.

Here you can see the result following the addition of prism layers. You can see that where there was original a sharp corner, a tapered edge has been produces, and downstream, a large number of malformed cells are visible on the lower edges.

Due to the pandemic I am working from home which is significantly increasing the time required to produce each mesh. I have been playing around with the settings in both 'snapControls' and 'addLayerControls', most notably the smoothing operations and primary iteration settings (including 'nFeatureSnapIter') but to no avail.

As a slight aside, one of the problems I was facing when using blockMesh to explicitly define my domain was that my prism layers were 'bulging' across the faces of the domain and 'compressing' (but not collapsing) towards the edges. I think it is to do with the fact that the domain has a slight divergence in width across its length, but had no luck counteracting that either.

I hope everyone is staying safe in these crazy times, and would me immensely grateful if any of the snappy wizards out there could shed some light on these issues.