On Wed, Aug 24, 2011 at 1:25 PM, Marek Schmitt <span dir="ltr"><<a href="mailto:marek.schmitt@yahoo.com">marek.schmitt@yahoo.com</a>></span> wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
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?<br></blockquote><div><br></div>
<div>PETSc is not primarily developed for discretization and topology. It solves systems of nonlinear algebraic equations. It does have</div><div>some extensions that handle structured (DMDA) and unstructured (DMMesh) under the recently developed DM interface.</div>
<div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Pylith and Fenics seem to use Sieve for unstructured grids. Is Sieve part of PETSc?<br></blockquote><div><br></div><div>Sieve is both the name of an interface (implemented by FEniCS) and an implementation of that interface (in PETSc).</div>
<div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Why is it so much hidden? The very silent sieve-dev mailing list exists since four years, but there is a recent post:<br></blockquote><div><br></div><div>I am not sure its hidden. I answer all the questions on the list. Its a big project for one person to support. I put most of</div>
<div>my time into supporting PyLith (<a href="http://geodynamics.org/cig/software/pylith">http://geodynamics.org/cig/software/pylith</a>) which uses it for parallel FEM simulation.</div><div>PETSc is 20 years old, so we have had time to make some components more robust.</div>
<div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
"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 <a href="http://lists.mcs.anl.gov/pipermail/sieve-dev/2010-October/000098.html" target="_blank">http://lists.mcs.anl.gov/pipermail/sieve-dev/2010-October/000098.html</a>)<br>
Is the sieve-dev list about a different sieve than what is used by Pylith and Fenics?<br></blockquote><div><br></div><div>They are two different implementations.</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
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.<br>
<br>
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)?<br></blockquote>
<div><br></div><div>You must use petsc-dev in order for the examples to work, like SNES ex12.</div><div><br></div><div> Thanks,</div><div><br></div><div> Matt</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Please shine some light into the mysterious Sieve.<br>
<font color="#888888">Marek<br>
</font></blockquote></div><br><br clear="all"><div><br></div>-- <br>What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.<br>
-- Norbert Wiener<br>