Hi, my code is the main part of my Master Thesis, so I need to talk with my professor about sharing it with the libmesh community. I uploaded my config.log here (http://pastebin.com/X3whQhLs) so you can check it. As far as I know I don't have PETSc installed/configured yet but there should be no problem to make up for this if this solves my problem. I also uploaded a shortened version of my code such that you can see what libmesh functions I'm using. Here is the link: http://pastebin.com/L9QrYkLQ Everything I removed from the code are computations of local matrix entries, copying those entries into 'Ke' and 'Fe' and accessing the pointers to the element's nodes (for their coordinates); so nothing that could crash the program or interfere with the system solving step...
Bye, Stephan Herb Am 14.09.2015 um 17:34 schrieb John Peterson: > > > On Mon, Sep 14, 2015 at 3:46 AM, Stephan Herb > <inf74...@stud.uni-stuttgart.de > <mailto:inf74...@stud.uni-stuttgart.de>> wrote: > > Hello, > > I wrote a code to compute displacements and drilling moments for flat > shell elements with FEM. It imports a mesh file (xda or msh), > assembles > the system matrix and RHS, solves the system and exports the > results as > vtk files. > When I run my program with one processor it all works fine and the > displacements are correct. The problem occurs with more than one > processor. > Simple example: Plane mesh (e.g. 8x8 quadrilaterals). Left edge is > clamped, the force is applied at the right edge and only at this edge. > If I run this example with e.g. 2 processors the partitioning cut > halves > the mesh in a left and a right part. The result looks as follows: The > left part has no displacement at all, while the right part has a huge > displacement. > > > So you implemented a new type of shell finite element in libmesh? It > would be great if this is something you could share with us in a > branch on GitHub... > > > I studied your example codes and couldn't see any special code > fragments > that is needed for a parallelized version of the code, so I thought: > 'Hey, libmesh seems to handle the parallelization internally - that's > great!'. But when I look at my results; in my opinion every processor > solves its own partial system with its own boundary condition, mesh > nodes and RHS and produces its own solution - so no communication or > exchange between the processes at all... > > > Are you using PETSc? Please send me (or share on google docs) your > config.log file so I can take a look at your system's configuration. > > > Now to my questions: Do I need additional configurations in my code to > make it work (at the LinearImplicitSystem, the mesh, the system > matrix, > etc.)? Additional MPI code to exchange values/vectors/matrices by my > own? Libmesh seems to use MPI communication extensively internally and > it's difficult for me right now to see where the problem is. > Perhaps you > can give me a hint to be back on track soon. > > > You shouldn't need to do anything too special. One big thing is to > make sure you use "active_local" element iterators instead of "active" > ones in your assembly routine if you are writing non-FEMSystem style > libmesh code. > ------------------------------------------------------------------------------ _______________________________________________ Libmesh-users mailing list Libmesh-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libmesh-users
