Axisymmetric problems with hexahedra

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Daniel
Posts: 20
Joined: Fri Feb 03, 2023 4:08 pm

Axisymmetric problems with hexahedra

Post by Daniel »

Hi.

I would like to know how to force GiD to mesh axisymmetric problems with hexahedra elements. I am getting a message saying that this is not possible for unstructured volumes, but I know GiD can build it.
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escolano
Posts: 1922
Joined: Sun Sep 05, 1982 10:51 pm

Re: Axisymmetric problems with hexahedra

Post by escolano »

Apart of the 'axisymmetric' adjective,
hexahedra unstructured meshes cannot be generated by GiD
must be structured (topologically a 6-faces cube)
or semi-structured (topologically a surface of arbitrary faces, extruded along a direction)

In this case 'axisymmetric', I guess that do you want a revolution mesh, then can do a semi-structured one, the extrusion direction is the revolution circumference.
Daniel
Posts: 20
Joined: Fri Feb 03, 2023 4:08 pm

Re: Axisymmetric problems with hexahedra

Post by Daniel »

OK.

I was able to generate a mesh by a semi-structured volume. I have searched by a revolution mesh, but didn't find. How can I do a mesh symmetrical with respect to a axis?
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escolano
Posts: 1922
Joined: Sun Sep 05, 1982 10:51 pm

Re: Axisymmetric problems with hexahedra

Post by escolano »

Can create a geometry or a mesh of revolution, with the Utilities->Copy window...

It the mesh is not enough 'symmetric' meshing a geometry created by revolution
the can do of copy directly in mesh: first create the 2D surface mesh (triangles or quadrilaterals) and then do a copy of these elements by revolution around an axis (defined by two coordinates in 3D, one in 2D) and with extrusion of elements to create prisms/hexahedra. Set a small degree and multiple copies, e.g. angle=15.0 degrees and copies=24 to fit the 360 degrees

At the end can delete the elements of surface, probably do you only want the elements of volume extruded

But it is unrecommended to work directly in mesh, it is better if possible do a geometry, assign groups, conditions, materials, layers and then generate the mesh.

It is usually more difficult the direct selection in mesh.
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