You may also want to take a look at the DMNetwork framework that can be used for general unstructured networks that don't use PDEs. Its description is given in the manual and an example is in src/snes/examples/tutorials/network/pflow.
Shri From: Matthew Knepley <knep...@gmail.com> Date: Tue, 23 Sep 2014 22:40:52 -0400 To: Miguel Angel Salazar de Troya <salazardetr...@gmail.com> Cc: "petsc-users@mcs.anl.gov" <petsc-users@mcs.anl.gov> Subject: Re: [petsc-users] DMPlex with spring elements >On Tue, Sep 23, 2014 at 4:01 PM, Miguel Angel Salazar de Troya ><salazardetr...@gmail.com> wrote: > >Hi all >I was wondering if it could be possible to build a model similar to the >example snes/ex12.c, but with spring elements (for elasticity) instead of >simplicial elements. Spring elements in a grid, therefore each element >would have two nodes and each node two components. There would be more >differences, because instead of calling the functions f0,f1,g0,g1,g2 and >g3 to build the residual and the jacobian, I would call a routine that >would build the residual vector and the jacobian matrix directly. I would >not have shape functions whatsoever. My problem is discrete, I don't have >a PDE and my equations are algebraic. What is the best way in petsc to >solve this problem? Is there any example that I can follow? Thanks in >advance > > > > >Yes, ex12 is fairly specific to FEM. However, I think the right tools for >what you want are >DMPlex and PetscSection. Here is how I would proceed: > > 1) Make a DMPlex that encodes a simple network that you wish to simulate > > 2) Make a PetscSection that gets the data layout right. Its hard from >the above > for me to understand where you degrees of freedom actually are. >This is usually > the hard part. > > 3) Calculate the residual, so you can check an exact solution. Here you >use the > PetscSectionGetDof/Offset() for each mesh piece that you are >interested in. Again, > its hard to be more specific when I do not understand your >discretization. > > Thanks, > > Matt > > >Miguel > > > >-- >Miguel Angel Salazar de Troya >Graduate Research Assistant >Department of Mechanical Science and Engineering >University of Illinois at Urbana-Champaign >(217) 550-2360 <tel:%28217%29%20550-2360> >salaz...@illinois.edu > > > > > > > > > >-- >What most experimenters take for granted before they begin their >experiments is infinitely more interesting than any results to which >their experiments lead. >-- Norbert Wiener
