[Gmsh] help: iron sheet with hole.

[Rui Maciel]

On 02/10/2013 07:30 PM, Javier Lopez wrote:
> Hi,
> I'm trying to mesh an iron sheet with several holes on it to see how an air
> flow pass through it.
> When I manage to mesh both volumes, I  tried simulate the system but the
> air flow it dosen't pass through the holes. another times it only mesh the
> bottom volume.
>
> Thanks in advance for your help

 From your description, it appears that you were trying to define two 
air volumes connected through the holes in the iron sheet.  Yet, your 
geometry file doesn't do that.  Instead, it only defines a set of 
volumes that overlap over themselves.

Here's the bad news: Gmsh doesn't support any form of boolean operations 
on geometrical entities.  So, to be able to define your model you will 
need to do a whole lot of heavy lifting to set a model that Gmsh is able 
to use to define a connected mesh.  That won't be a pick-nick.

As far as I can tell, the simplest way to get a working model is to 
start by defining the iron sheet.  After you make sure that Gmsh is 
properly meshing the iron sheet then you move on to the air volumes, 
which can be defined by extruding the iron sheet surfaces, including the 
air holes, towards both sides.  Finally, when that works out, just 
expand one of the air volumes by extruding one of its surfaces.

This is no easy task, but as Gmsh doesn't do constructive solid geometry 
then you don't have much of a choice.


Hope this helps,
Rui Maciel