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From: Shaoying Lu <sylu@bi...>  20040803 18:36:43

Hello, I have been using libmesh for some reactiondiffusion simulation for a while. I found that libmesh is well written and easy to use. Now I have a quesion about the BoundaryInfo class. In my project, I am trying to initialize a mesh with the boundary faces being tagged by an integer number, to implement different boundary conditions later. I found this can be realized by using the BoundaryInfo class. However, there is not much documentation. I'd appreciate if anyone could point me to an example or give me a chunk of code which shows how the BoundaryInfo class is initialized. Thank you very much! Kathy 
From: Shaoying Lu <sylu@bi...>  20040803 23:18:11

Hi John, Thanks for the reply. It is really helpful. Now I have an additional question. I have been using netgen to generate my mesh, since tetgen does not some function I needed. After that I was able to convert my mesh to the tetgen format, with three files mesh.node, mesh.face, mesh.ele. Libmesh has support for tetgen. In my tests, it can read the mesh and solve the equations. However I found in the TetGenIO::read() function the surface file mesh.face is ignored. Therefore there is no way to input the boundary surface tag together with the mesh. I am wondering if there will be some solution to the problem soon, or I need to find a way to work around this. Any suggestion or comments will be appreciated. Thanks! kathy On Tue, 3 Aug 2004, John Peterson wrote: > Hi, > > Assuming you have a Mesh called "mesh": > > BoundaryMesh boundary_mesh (mesh.mesh_dimension()1); > mesh.boundary_info.sync(boundary_mesh, false); > > > Good luck, > John > > > Shaoying Lu writes: > > Hello, > > > > I have been using libmesh for some reactiondiffusion simulation for a > > while. I found that libmesh is well written and easy to use. Now > > I have a quesion about the BoundaryInfo class. > > > > In my project, I am trying to initialize a mesh with the boundary faces > > being tagged by an integer number, to implement different boundary > > conditions later. I found this can be realized by using the BoundaryInfo > > class. However, there is not much documentation. I'd appreciate > > if anyone could point me to an example or give me a chunk of code which > > shows how the BoundaryInfo class is initialized. > > > > Thank you very much! > > > > Kathy > 
From: John Peterson <peterson@cf...>  20040803 23:51:10

Hi, The TetGen interface was written by Steffen Petersen, so I am not too familiar with it. In your code, could you open and parse the "mesh.face" file yourself and use its information? Otherwise, I have to pass this question off to Steffen. John Shaoying Lu writes: > Hi John, > > Thanks for the reply. It is really helpful. Now I have an > additional question. > > I have been using netgen to generate my mesh, since tetgen does > not some function I needed. After that I was able to convert my mesh > to the tetgen format, with three files mesh.node, mesh.face, mesh.ele. > > Libmesh has support for tetgen. In my tests, it can read the mesh and > solve the equations. However I found in the TetGenIO::read() function the > surface file mesh.face is ignored. Therefore there is no way to input the > boundary surface tag together with the mesh. I am wondering if there will > be some solution to the problem soon, or I need to find a way to work > around this. > > Any suggestion or comments will be appreciated. > > Thanks! > 
From: Steffen Petersen <steffen.petersen@tu...>  20040810 16:21:54

> Hi John, > > Thanks for the reply. It is really helpful. Now I have an > additional question. > > I have been using netgen to generate my mesh, since tetgen > does not some function I needed. After that I was able to > convert my mesh to the tetgen format, with three files > mesh.node, mesh.face, mesh.ele. > > Libmesh has support for tetgen. In my tests, it can read the > mesh and solve the equations. However I found in the > TetGenIO::read() function the surface file mesh.face is > ignored. Therefore there is no way to input the boundary > surface tag together with the mesh. I am wondering if there > will be some solution to the problem soon, or I need to find > a way to work around this. > We may consider the .face file in the TetGenIO::read() method soon. Can you perhaps send an example (i.e. .node .face .ele files) for testing? Steffen 
From: Shaoying Lu <sylu@bi...>  20040812 18:25:06

Thanks to all the replies about the boundary conditions and tetgen, recently I have been able to succesfully enforce neuman boudnary conditions with tetgen and libmesh. I wrote a new class TetGenIOExt, as an extension of the class TetGenIO, enabling one to read in tetgen mesh with the boundary face tagging. Please feel free to include it in libmesh. Attatched please find the following files: tetgen_io_ext.h, tetgen_io_ext.C, together with the tetgen input files cube.1.node, cube.1.face, cube.1.ele. The mesh may be read by: TetGenIOExt(mesh).read(mesh_file_name); best, Kathy On Tue, 10 Aug 2004, Steffen Petersen wrote: > > Hi John, > > > > Thanks for the reply. It is really helpful. Now I have an > > additional question. > > > > I have been using netgen to generate my mesh, since tetgen > > does not some function I needed. After that I was able to > > convert my mesh to the tetgen format, with three files > > mesh.node, mesh.face, mesh.ele. > > > > Libmesh has support for tetgen. In my tests, it can read the > > mesh and solve the equations. However I found in the > > TetGenIO::read() function the surface file mesh.face is > > ignored. Therefore there is no way to input the boundary > > surface tag together with the mesh. I am wondering if there > > will be some solution to the problem soon, or I need to find > > a way to work around this. > > > > We may consider the .face file in the TetGenIO::read() method > soon. Can you perhaps send an example (i.e. .node .face .ele files) > for testing? > > Steffen > 
From: John Peterson <peterson@cf...>  20040803 19:26:28

Hi, Assuming you have a Mesh called "mesh": BoundaryMesh boundary_mesh (mesh.mesh_dimension()1); mesh.boundary_info.sync(boundary_mesh, false); Good luck, John Shaoying Lu writes: > Hello, > > I have been using libmesh for some reactiondiffusion simulation for a > while. I found that libmesh is well written and easy to use. Now > I have a quesion about the BoundaryInfo class. > > In my project, I am trying to initialize a mesh with the boundary faces > being tagged by an integer number, to implement different boundary > conditions later. I found this can be realized by using the BoundaryInfo > class. However, there is not much documentation. I'd appreciate > if anyone could point me to an example or give me a chunk of code which > shows how the BoundaryInfo class is initialized. > > Thank you very much! > > Kathy 
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