<div dir="ltr"><div class="gmail_extra">Hi,<br><div class="gmail_quote">On Mon, Feb 24, 2014 at 11:30 PM, Aron Roland <span dir="ltr"><<a href="mailto:aaronroland@gmx.de" target="_blank">aaronroland@gmx.de</a>></span> wrote:<br>
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<div>Hi, <br>
<br>
I can provide u some nice package to generate unstructured meshes.
There are many institutions using it now.</div></div></blockquote><div><br></div><div>Yes, that would be great. Thanks !</div><div><br></div><div>Saludos,</div><div>Christophe</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000"><div> We have also used PETSC
to solve some nonlinera hyperbolic problem on 2d on unstructured
meshes and it works quite ok even if the scaling still not what it
should be but well these are other issues ...<br>
<br>
Cheers<span class="HOEnZb"><font color="#888888"><br>
<br>
Aron</font></span><div><div class="h5"><br>
<br>
On 02/24/2014 09:04 AM, Christophe Ortiz wrote:<br>
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<div class="gmail_extra"><br>
<div class="gmail_quote">On Sat, Feb 22, 2014 at 2:33 AM, Jed
Brown <span dir="ltr"><<a href="mailto:jed@jedbrown.org" target="_blank">jed@jedbrown.org</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<div>Christophe Ortiz <<a href="mailto:christophe.ortiz@ciemat.es" target="_blank">christophe.ortiz@ciemat.es</a>>
writes:<br>
<br>
> Hi all,<br>
><br>
> Recently I have implemented a 1D problem of coupled
diffusion equations<br>
> using PETSc. I did it using finite differences for
diffusion terms and<br>
> F(t,U,U_t) = 0. It works pretty well with ARKIMEX3.
I get a nice timestep<br>
> variation and all boundary conditions work well.<br>
><br>
> Now I would like to move to 3D problems to simulate
the diffusion and<br>
> interaction of species in a "real material". By
real material I mean a<br>
> material made of subregions with internal surfaces
where species could<br>
> recombine (means Dirichlet). These subregions are
distributed in a<br>
> complicated manner, ie not cartesian. A good
picture of this would be a<br>
> polycrystal (see attachment to get an idea). Each
crystal has a different<br>
> orientation and the boundary between two small
crystals forms an internal<br>
> surface.<br>
><br>
> I have several questions on how to implement this:<br>
><br>
> 1) Since, the problem will not be solved in a
cartesian mesh, should I use<br>
> unstructured meshes ? If so, how can this
unstructured mesh can be<br>
> generated ( I have no experience with unstructured
meshes. I always work in<br>
> 1D).<br>
<br>
</div>
Are you intending to mesh the boundaries of the crystals?
Will you be<br>
dynamically remeshing? (That is very complicated and
expensive in 3D.)<br>
</blockquote>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">What
formulation will you be using for grain boundary
evolution?<br>
<br>
</blockquote>
<div><br>
</div>
<div>No, in principle I will not consider the evolution of
grains. Therefore, no dynamic remershing (in principle).<br>
</div>
<div>What I want is just the evolution of diffusing and
reacting species inside the ensemble of grains, including
their interaction with the grain boundaries (trapping,
segregation, ...).</div>
<div> </div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">I
think you should check out phase field models, such as the
publication<br>
below. </blockquote>
<div><br>
</div>
<div>I never used phase-field models. According to what I
read, it can model many phnomena but in particular it
substitutes a boundary condition at an interface by a PDE
for the evolution of an auxiliary field (Wikipedia). In
this sense, maybe it could be interesting since I want to
simulate the evolution of species inside grains with many
internal grain boundaries.</div>
<div>But I don't know if to treat a grain boundary as a
infinitely sharp interface or as a thin but finite piece
of material with different properties for species
(diffusion coeff for instance).</div>
<div><br>
</div>
<div>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"> Perhaps
check out the paper below. The framework (MOOSE) used<br>
for this publication should be released open source on
github next week<br>
(check <a href="https://github.com/idaholab/" target="_blank">https://github.com/idaholab/</a>).
I don't know if Marmot, the<br>
phase-field component, will be open source any time soon,
but they are<br>
typically happy to collaborate. MOOSE uses PETSc for
solvers, but<br>
provides a higher level interface.<br>
<br>
@article{tonks2012object,<br>
title={An object-oriented finite element framework for
multiphysics phase field simulations},<br>
author={Tonks, M.R. and Gaston, D. and Millett, P.C. and
Andrs, D. and Talbot, P.},<br>
journal={Computational Materials Science},<br>
volume={51},<br>
number={1},<br>
pages={20--29},<br>
year={2012},<br>
publisher={Elsevier}<br>
}<br>
<br>
</blockquote>
<div><br>
</div>
<div>Sorry, I could not download the article. We don't have
access. Crisis in Spain :-( !</div>
<div> </div>
</div>
<br>
</div>
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<br>
</div></div></div>
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