petsc and x-fem

[Farshid Mossaiby]

Hi,

I always liked idea of a *simple* parallel FEM code in Petsc, which shows most of tricks used in various programs, like parallel assembly of elements and imposing Dirichlet BCs in a proper way. I think this can eliminate many of "How should I do that" questions from newbies like me. I think this is almost a series of copy-paste's for you. With a little documentation this would be a great help.

Best regards,
Farshid Mossaiby


--- On Tue, 8/12/08, Barry Smith <bsmith at mcs.anl.gov> wrote:

> From: Barry Smith <bsmith at mcs.anl.gov>
> Subject: Re: petsc and x-fem
> To: petsc-dev at mcs.anl.gov
> Cc: "Techas" <techas at gmail.com>
> Date: Tuesday, August 12, 2008, 7:48 PM
> There is also one other example that is a lower level then
> sieve
> where the application more directly manages the mesh data
> structure.
> This is example is src/snes/examples/tutorials/ex10d. It is
> not really
> a complete example but gives the outline of how one can
> write
> such a code.
> 
>     Barry
> 
> On Aug 12, 2008, at 6:28 AM, Matthew Knepley wrote:
> 
> > On Mon, Aug 4, 2008 at 6:49 AM, Techas
> <techas at gmail.com> wrote:
> > Hi Matthew,
> >
> > I'm Sergio (X-FEM), we meet some weeks ago in
> Davis.
> > I'm playing a little bit with petsc to evaluate
> how much work will
> > take me mount my x-fem code on petsc.
> >
> > Sorry I am just replying now. I returned from Norway
> yesterday.
> >
> >
> > My first question is: can you tell me a good example
> of the assembly
> > of a global finite element matrix (distributed in n
> procs) based on a
> > distributed mesh?
> >
> > The answers is in two parts. If you have a structured
> grid, then the  
> > DA
> > construct can do everything and is very simple. You
> just call  
> > MatSetValuesStencil()
> > as in KSP ex2.
> >
> > If you have an unstructured grid, we have new
> functionality (only in  
> > the
> > development version) in a Mesh object. This will be in
> the upcoming  
> > release,
> > but you can see it now in
> src/dm/mesh/sieve/problems/Bratu.hh. The  
> > function
> > to examine is Rhs_Unstructured() which forms the
> residual for this  
> > equation
> > on an unstructured mesh. Unfortunately, this is new
> and has little  
> > documentation.
> > Before the release, I will write some, but until then
> you will have  
> > to ask me
> > questions if you want to try it out.
> >
> >   Thanks,
> >
> >      Matt
> >
> >
> > If you want me to write to the petsc list just tell
> me.
> >
> > thank you!
> > Sergio.
> >
> > --
> > Sergio Zlotnik, PhD
> > Group of Dynamics of the Lithosphere -GDL-
> > Department of Geophysics & Tectonics
> > Institute of Earth Sciences - CSIC
> > Sole Sabaris s/n
> > Barcelona 08028 - SPAIN
> >
> > Tel: +34 93 409 54 10
> > Fax: +34 93 411 00 12
> > email: szlotnik at ija.csic.es
> >
> > Web page http://www.ija.csic.es/gt/sergioz/
> >
> >
> >
> > -- 
> > 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