ElmerGrid issue with boundaries

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millim
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ElmerGrid issue with boundaries

Post by millim » 22 Aug 2013, 12:19

Hi,

for a multiphysics problem I want to define several boundary surfaces using Salome and UNV Mesh and proper grouping. In some cases one body surface element has to belong to more than one boundary definition. Unfortunately, Elmergird does an unwanted union to a single boundary. How can this be resolved?

See the Elmergrid Code

Code: Select all

Reading node coordinates
Reading element topologies
Reading element groups in mode 2467
Reading 1:th group with index 1 with 4862 entities: Solid_4
Element type range in group is [504 504]
Reading 2:th group with index 2 with 42820 entities: Solid_2
Element type range in group is [504 504]
Reading 3:th group with index 3 with 6617 entities: Solid_3
Element type range in group is [504 504]
Reading 4:th group with index 4 with 5380 entities: Solid_1
Element type range in group is [504 504]
Reading 5:th group with index 5 with 2 entities: V0
Element type range in group is [303 303]
Reading 6:th group with index 6 with 2 entities: V1
Element type range in group is [303 303]
Reading 7:th group with index 7 with 140 entities: Space
Element type range in group is [303 303]
Reading 8:th group with index 8 with 3538 entities: Metal
Element type range in group is [303 303]
Reading 9:th group with index 9 with 4412 entities: Conductor
Element type range in group is [303 303]
Moving bulk elements to boundary elements
Leading bulk elementtype is 504
Trailing bulk elementtype is 202
There are 12726 (out of 72405) lower dimensional elements.
Node 5648 belongs to maximum of 52 elements
Found 9814 side elements that have two parents.
Found correctly 12726 side elements.
Parent elements were reordered up to indx 59679.
Moved 59679 elements (out of 72405) to new positions
The Universal mesh was loaded from file mesh.unv.


Elmergrid creating and manipulating meshes:
-------------------------------------------
Removing lower dimensional boundaries
Maximum elementtype is 504 and dimension 3
Removed 2772 (out of 12726) less than 3D boundary elements
All 10249 nodes were used by the mesh elements
Initial boundary interval [7,10]
boundary index changed 7 -> 1 in 140 elements
boundary index changed 8 -> 2 in 3538 elements
boundary index changed 9 -> 3 in 4412 elements
boundary index changed 10 -> 4 in 1864 elements
Mapping boundary types from [7 10] to [1 4]
Initial body interval [1,4]
body index changed 1 -> 1 in 4862 elements
body index changed 2 -> 2 in 42820 elements
body index changed 3 -> 3 in 6617 elements
body index changed 4 -> 4 in 5380 elements
Numbering of bodies is ok!

Elmergrid saving data with method 2:
-------------------------------------
Saving mesh in ElmerSolver format to directory mesh.
Reusing an existing directory
Saving 10249 coordinates to mesh.nodes.
Saving 59679 element topologies to mesh.elements.
Saving boundary elements to mesh.boundary.
Saving header info to mesh.header.
Saving names info to mesh.names.


Initial boundary interval should be [5,10] instead of [7,10]. As described: Boundaries 5,6 are a subset of 9

raback
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Re: ElmerGrid issue with boundaries

Post by raback » 22 Aug 2013, 16:57

Hi

The question is very much related to this one:
viewtopic.php?f=15&t=3175

So the limitation is that Elmer has currently only one BC tag. If the elements belong to several groups what should be done with them?
  • To allow for several tags (major revision)?
  • To make redundant copies of the same element?
  • To take the union and give it a different tag?
From coding point of view the 2nd one would be of least work in ElmerGrid.

-Peter

millim
Posts: 39
Joined: 04 Apr 2012, 14:58
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Re: ElmerGrid issue with boundaries

Post by millim » 23 Aug 2013, 00:44

Hi Peter,

thx for your valuable answer. I solved it (at least for my target problem) by avoiding overlapping boundaries in Salome grouping. I have overseen the simple possibility of union of surfaces in the boundary descriptor.

Thx

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