COMSOL Forums: do i need extra advanced module to get 9-node 'quad2' meshes?

Re: do i need extra advanced module to get 9-node 'quad2' meshes?

Sat, 13 Mar 2010 07:45:59 +0000

Hi

I havent found your page 633, probably we have a different version of the doc, (or I have lost one, easily done).

But for me, I would not save more than required, I understand that quad-4nodes, quad-5nodes quad-9nodes are just "quads" with 4 corners and then extra nodes at given relative position w.r.t. these four basic nodes, so from my understanding these are higher order "help" functions on top of the simple(st) mesh.

So it could well be that the extra nodes are not explicitely exported in the mesh file, but just tagged as a specific "element quality".

I have not understood that you need specific modules to get general FEM functionalities, only for the specific predefined equations, but I do not know everything of what happening insiode COMSOL ;)

Good luck
Ivar

Re: do i need extra advanced module to get 9-node 'quad2' meshes?

Fri, 12 Mar 2010 20:43:29 +0000

well, let me ask this question first.

Can COMSOL export 9 node quad elements generated for 2d problem?

If so, my question is how I do this?

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According to the referecnce manual, COMSOL supports a Quadrilateral element (quad2), pp.141. How do I choose this mesh?

I have been trying different 'predefined element settings' under 'Subdomain Settings.' however, whenever I export a mphtxt file, it always comes out with 'quad' not 'quad2'.

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Since I dont have any extra module, I am wondering if I need one of those to get my geometry meshed with 'quad2' elements and exported it to mphtxt file.

By the way, can 'quad2' elements be exported to a mphtxt file?
I can see the following example in pp. 633 of 'reference guide'

# Type #6
5 quad2 # type name
9 # number of nodes per element
102 # number of elements
# Elements
85 90 476 557 118 499 1170 566 563
85 476 174 474 499 221 1171 496 494
.......

I think I should be able to export 9node elements....I just dont know how.

Thanks for reading and replying.... in advnce

Sangpil

Re: do i need extra advanced module to get 9-node 'quad2' meshes?

Fri, 12 Mar 2010 19:47:38 +0000

Hi

I do not fully understand your question, for me use the quad mesh (and not the thet/tri) on a rectangle, and define the shape type to be a higher order in the physics, is it that you are looking for ?

Good luck
Ivar

do i need extra advanced module to get 9-node 'quad2' meshes?

Fri, 12 Mar 2010 18:27:47 +0000

I am looking for way to get meshes in 9 nodes 2d elements and export it to mphtxt file so that I can read 'quad2' information.

(In mphtxt format, 'quad' is for 4-node elements and 'quad2' is for 9-node elements)

How do I get discretize the geometry with quad2 elements?

Do I need an extra advanced module to mesh 2d geometry?

Thanks for reading and replying in advance.