[mesh manipulation] DynamicMesh - Move internal points

nucat · September 4, 2014, 16:29

Hallo foamers,

actually I am programming an y+ adaption for OpenFoam. I need a tool, which manipulates the mesh by making the thickness of the first boundary layer smaller if there is detected y+>1.

I am able to detect that vertices with toposet:

select all faces with y+>1
select all cells with that selected faces
select points of the selected cells (first boundary layer)
deselect points of the boundary face

The result is a selection of points of the first boundary cells, but not points directly of the boundary (they have to stay fixed). Now I want to move them down and want to do it with dynamicMesh library.

Problem: I didn't find in the web a tutorial, how to move internal points (not boundary points) of the mesh. Do anybody knows how it works?

Thanks for help,
Nucat

mturcios777 · September 4, 2014, 19:35

If you look at the layeredEngineMesh code, you can see there is code that moves certain mesh points to a new position based on the calculated crank angle. You will need to do something similar, although I don't quite know how you would determine the new position.

It would have to be some kind of function that finds distance to the nearest point on a boundary patch, then takes a fraction of the distance along the vector to the nearest point on the patch and moves the new point to that position (like half the distance?). Or just a set distance along that line. There are some built in functions like that in meshTools and other libraries. Its been a while since I've had to do anything with them.

nucat · September 6, 2014, 09:54

Hey,

thanks for reply. I think I will solve that problem by myself with toposet and python ))

September 4, 2014, 16:29	DynamicMesh - Move internal points	#1
nucat New Member Join Date: Jan 2013 Posts: 10 Rep Power: 13	Hallo foamers, actually I am programming an y+ adaption for OpenFoam. I need a tool, which manipulates the mesh by making the thickness of the first boundary layer smaller if there is detected y+>1. I am able to detect that vertices with toposet: select all faces with y+>1 select all cells with that selected faces select points of the selected cells (first boundary layer) deselect points of the boundary face The result is a selection of points of the first boundary cells, but not points directly of the boundary (they have to stay fixed). Now I want to move them down and want to do it with dynamicMesh library. Problem: I didn't find in the web a tutorial, how to move internal points (not boundary points) of the mesh. Do anybody knows how it works? Thanks for help, Nucat

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September 4, 2014, 19:35		#2
mturcios777 Senior Member Marco A. Turcios Join Date: Mar 2009 Location: Vancouver, BC, Canada Posts: 740 Rep Power: 28	If you look at the layeredEngineMesh code, you can see there is code that moves certain mesh points to a new position based on the calculated crank angle. You will need to do something similar, although I don't quite know how you would determine the new position. It would have to be some kind of function that finds distance to the nearest point on a boundary patch, then takes a fraction of the distance along the vector to the nearest point on the patch and moves the new point to that position (like half the distance?). Or just a set distance along that line. There are some built in functions like that in meshTools and other libraries. Its been a while since I've had to do anything with them.

September 6, 2014, 09:54		#3
nucat New Member Join Date: Jan 2013 Posts: 10 Rep Power: 13	Hey, thanks for reply. I think I will solve that problem by myself with toposet and python ))