[Gmsh] Reversing mesh normals

[Mark Smith]

Hi Gmsh users,
I have a gmsh format mesh produced in pointwise which I load into gmsh. I wish to reverse the direction of the surface normals on the mesh which I do by options>mesh>color>Reverse all normal, if I set mesh.normals to some non zero value the normal vector is displayed on the surface mesh and reverse all normal does indeed reverse the vectors direction BUT if I save the mesh out to gmsh msh format with the normals reversed then load it back into gmsh the normal direction is the same as the original, am I doing something wrong or is what I want to do not possible?

Also Is it possible to only reverse the normals on certain mesh surfaces rather than all?

Is there a way to define Physical groups on a mesh rather than on Geometry if one only has a mesh?

Thanks in advance
Best regards
Mark

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