[CAD formats] BC at specific location in STL mesh

sam mas · November 21, 2014, 16:10

Dear all,

I want to apply Neumann type boundary condition at specific locations of a surface STL mesh. Any suggestion on how can this be done? By specific location, I do not mean at specific points, I mean specific areas on the surface.

An example would be much appreciated.

Many thanks in advance

chegdan · November 21, 2014, 16:24

Short Answer: split your STL into separate STL files for each BC, mesh in snappyHexMesh.

sam mas · November 21, 2014, 16:47

Thanks Dan for a quick reply.

If possible can you please recommend any example/ tutorial?

sam

chegdan · November 21, 2014, 16:58

look in tutorials/mesh/snappyHexMesh/ at how they setup snappyhexMesh. you would need entries in your snappyHexMeshDict for each STL in the geometry and castellatedMeshControls>refinementSurfaces sections of the dictionary. There are multiple GUIs that can help with this (see section 2). Good luck

simpomann · November 24, 2014, 11:09

I would split the STL with a seperate preprocessor, like CATIA's Rapid Prototyping environment or Ansys' Ansa.
If it has very few triangles you might do it by hand (an ASCII-STL is basically a list of triangles) and can be split in multiple regions (marked with solid, closed with endsolid). You can then adress each region seperately as a patch, e.g.
MyGeomety_region1
MyGeometry_region2
Where region is the solid name within the STL-file.

Like this you can adress them within snappyHexMesh, e.g. to use different refinements, as well as in the patch field files for boundaries 0/U etc.

In the default snappyHexMeshDict under applications/utilities/mesh/generation/snappyHexMesh should be an example how to use this

November 21, 2014, 16:10	BC at specific location in STL mesh	#1
sam mas New Member sam mas Join Date: Nov 2014 Posts: 2 Rep Power: 0	Dear all, I want to apply Neumann type boundary condition at specific locations of a surface STL mesh. Any suggestion on how can this be done? By specific location, I do not mean at specific points, I mean specific areas on the surface. An example would be much appreciated. Many thanks in advance

November 21, 2014, 16:47	Thanks Dan	#3
sam mas New Member sam mas Join Date: Nov 2014 Posts: 2 Rep Power: 0	Thanks Dan for a quick reply. If possible can you please recommend any example/ tutorial? sam

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November 21, 2014, 16:24		#2
chegdan Senior Member Daniel P. Combest Join Date: Mar 2009 Location: St. Louis, USA Posts: 621 Rep Power: 0	Short Answer: split your STL into separate STL files for each BC, mesh in snappyHexMesh.

November 21, 2014, 16:58		#4
chegdan Senior Member Daniel P. Combest Join Date: Mar 2009 Location: St. Louis, USA Posts: 621 Rep Power: 0	look in tutorials/mesh/snappyHexMesh/ at how they setup snappyhexMesh. you would need entries in your snappyHexMeshDict for each STL in the geometry and castellatedMeshControls>refinementSurfaces sections of the dictionary. There are multiple GUIs that can help with this (see section 2). Good luck

November 24, 2014, 11:09		#5
simpomann Member Simon Arne Join Date: May 2012 Posts: 42 Rep Power: 13	I would split the STL with a seperate preprocessor, like CATIA's Rapid Prototyping environment or Ansys' Ansa. If it has very few triangles you might do it by hand (an ASCII-STL is basically a list of triangles) and can be split in multiple regions (marked with solid, closed with endsolid). You can then adress each region seperately as a patch, e.g. MyGeomety_region1 MyGeometry_region2 Where region is the solid name within the STL-file. Like this you can adress them within snappyHexMesh, e.g. to use different refinements, as well as in the patch field files for boundaries 0/U etc. In the default snappyHexMeshDict under applications/utilities/mesh/generation/snappyHexMesh should be an example how to use this