[petsc-users] DMPlex with spring elements

[Abhyankar, Shrirang G.]

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 <knepley at gmail.com>
Date:  Tue, 23 Sep 2014 22:40:52 -0400
To:  Miguel Angel Salazar de Troya <salazardetroya at gmail.com>
Cc:  "petsc-users at mcs.anl.gov" <petsc-users at 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
><salazardetroya at 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>
>salaza11 at 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