[petsc-users] PETSc on unstructured meshes / Sieve

[Gong Ding]

----- Original Message ----- 
From: "Marek Schmitt" <marek.schmitt at yahoo.com>
To: <petsc-users at mcs.anl.gov>
Sent: Wednesday, August 24, 2011 9:25 PM
Subject: [petsc-users] PETSc on unstructured meshes / Sieve


>I would like to experiment with PETSc for learning FVM on unstructured grids. I get the impression that PETSc is primarily developed for structured grids with cartesian topology, is this true?
> 
> Pylith and Fenics seem to use Sieve for unstructured grids. Is Sieve part of PETSc?
> Why is it so much hidden? The very silent sieve-dev mailing list exists since four years, but there is a recent post:
> "2) Unstructured meshes. This is not well-documented. There is a tutorial presentation and a repository of code for it. A few people have used this, but it is nowhere near the level of clarity and robustness that the rest of PETSc has." (from http://lists.mcs.anl.gov/pipermail/sieve-dev/2010-October/000098.html)
> Is the sieve-dev list about a different sieve than what is used by Pylith and Fenics?
> 
> There is a PETSc FAQ "Do you have examples of doing unstructured grid finite element computations (FEM) with PETSc?". It mentions Sieve but no further links or documentation.
> 
> Is the directory petsc-3.1-p8/include/sieve all that is needed to work with Sieve? Or are these only header files, and I have to link to the Sieve library from somewhere else (then where can I find Sieve)?
> 
> Please shine some light into the mysterious Sieve.
> Marek

Petsc is more or less a (linear) solver toolkit, not unstructured framework.
Libmesh can be a good start point to you. It is really a beautiful design. 
And some other framework, i.e. deal.II, openfoam.