[MOAB-dev] Problems with remove_adjacencies

[Iulian Grindeanu]

----- Original Message -----
| Hi there,
| I am having a problem with remove adjacencies so was wondering if I
| could get some help/advice.
| Basically I am working on a fracture mechanics problem so am looking
| to insert a crack into a mesh. As such I am splitting elements
| (tetrahedrons) along their faces. When I do this I insert a new node
| into the mesh and change the connectivity of some tets (along with
| their corresponding faces and edges). However, at this point I need to
| remove adjacencies which are still present across the crack face and
| for some reason when I am doing the remove_adjacencies function
| nothing is happening. I have done get_adjacencies directly after this
| function to check if it was being removed and it isn't.
Hello, It would be good to show in a piece of code / example what are you doing. In general, moab stores up-vertex adjacencies; (so, internally, a vertex has a list of entities it is connected to; edges, faces, solid elements) Adjacencies edge-face, face-solid element, edge-solid element, are not stored, UNLESS the user explicitly requests it, with "add_adjacency" methods. When the user requests for an edge, the faces adjacent to it, moab will actually construct that array, based on vertex -face adjacency (so it gets the nodes connected to the edge, then gets the faces connected to those vertices, and filters out the faces that do not contain the initial edge) (of course, unless you "stored" it explicitly before) If you store explicitly the edge-face adjacency, then the "remove" will have your expected effect. My guess is that if you need to "create" a crack, maybe you will have to first duplicate some mesh entities. Will the crack be across faces of tetras? You may have to duplicate the face, edges, even some vertices, before you can do a "separation" An edge, or a face, or an element will always be connected to its vertices, this is why I think you may need to duplicate some before separating for the crack. | So I was wondering if meshsets affect the implementation of
| remove_adjacencies or if there is any other advice you could give me
| regarding this function?
there is a connection between meshsets and adjacencies, for meshsets created with "TRACK" option. In the sense that it is stored in a similar way, but other than that, it should not be affected. I hope this helps, Iulian | Regards
| Graeme
| --------------------
| Graeme A. Edwards
| PhD Student - Materials & Mechanics Research Group
| School of Engineering
| University of Glasgow
| Rankine Building
| Oakfield Avenue
| G12 8LT
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