SimScale CAE Forum

Material point option in hex-dominant / snappyHexMesh operation


#1

Good afternoon SimScale Team.
Could you tell me, what is it Material point and how it influence on mesh, while using SnappHex Mesh. I could not find and information in documentation. Sorry, if I chose wrong Topic.


What is the Material Point?
#2

@Igarizza, the material point basically defines “where the mesh is”.

The snappyHexMesh operation starts with a cartesian grid that fills the complete bounding box (the blue box you need to define). So let’s assume you uploaded a CAD model of the fluid volume of a pipe and you chose the bounding box to be aligned with the pipe model on all sides. Then the mesh initially will be both inside as well as outside the pipe. In one step of this mesh operation. Now in one step of the snappyHexMesh operation, the material point is used to decide which part of the mesh to keep and which not. So if you chose the material point to be inside the pipe, the cells outside the CAD model will be deleted (which is probably what you want in such a setup). However in case you would rather be looking into an external flow analysis of the pipe (just for the sake of explaining this ;)) the material point would need to be outside.

This also makes clear why it’s important to have a closed CAD model (“watertight”) when using the snappyHexMesh operation because otherwise, it might simply mesh both “sides” of the model - inside and outside. Hope I could help!


CFD Analysis - Alfa Romeo P2 1930
Meshing failes.. unsure why
Geometry Disappearing when Meshing
Mesh problem
'exhaust' simulation project by stevenlewis
Mesh is ignoring CAD altogether
#3

@dheiny Thanks a lot!
I think you should to add this information in documents of HEX mesh)


#4

@Igarizza, absolutely! Already in progress - the hex-dominant mesh operation documentation is being updated right now also with more examples. Should be available soon!


#5

If I could suggest something in terms of Material Point it would be request for making it bigger and in different colour so that to make it visible :slight_smile:


#6

@Maciek, we are in the process of improving the workflow from CAD to Mesh. Once it’s ready for user testing, I would get back to you if that’s fine :smile: