[Gmsh] surface normals: some point inwards, but most point in the negative direction

[Christophe Geuzaine]

Matthias G. Imhof wrote:
> I defined a simple rectangular block and noticed that normals in the 
> x-direction actually change signs depending on the surface to point into 
> the block, while the other normals point in the negative y- or 
> z-directions pointing into the block for some surfaces and pointing 
> outwards for others.
> 
> How can I change this model to have all normals point out of the block?

The only way is to define Physical Surfaces with the appropriate sign, 
e.g. "Physical Surface(1) = {23,1,20,3,2,-16};". This will reverse the 
orientation of the surface 16 in the output mesh file.

> 
> A second question for the same problem. If I generate a quantity by 
> duplicate, how can I lates access this quantity? I tried to assign it 
> to, e.g., a plane surface but that did not work.

There is unfortunately no way to access that information at the moment 
without using the GUI...

Christophe

-- 
Christophe Geuzaine

Tel: (626) 395-4552    http://www.geuz.org
Fax: (626) 578-0124    mailto:geuzaine at acm.caltech.edu