[petsc-users] implementation of multi-level grid in petsc

[Mark F. Adams]

On Aug 8, 2013, at 3:32 PM, Roc Wang <pengxwang at hotmail.com> wrote:

> Thanks Mat,
> 
>     I tried Chombo for implementing AMR but not tried SAMRAI yet. Chombo can do AMR, but it seems the data structure is quite complicated for customizing usage.  What I want to do with petsc is to compose a simple "home-made" like blocked multi-level grid, though it is not automatically adaptive.  However, I don't have too much experiences on petsc. As of now, I suppose to use DM to manage the data for the big domain and all small sub-domains.  I am not sure whether it is a good idea.  So, any suggestions are appreciated very much.  Thanks again.
> 

As Matt said, this is not what you want to do, most likely.  Building AMR on DM/DA is a lot of work unless you have a simple application and have a clear idea of how to do it.  Chombo is flexible but it is complex and takes time to get started.  I'm not familiar wit SAMARI but I would guess it is like Chombo.  Deall.II might be worth looking into.  I'm not familiar.

> Best,
> 
> 
>     
> 
> Date: Thu, 8 Aug 2013 14:03:53 -0500
> Subject: Re: [petsc-users] implementation of multi-level grid in petsc
> From: knepley at gmail.com
> To: pengxwang at hotmail.com
> CC: petsc-users at mcs.anl.gov
> 
> On Thu, Aug 8, 2013 at 1:29 PM, Roc Wang <pengxwang at hotmail.com> wrote:
> Hi,
> 
>     I am working on multi-level grid for Poisson equation.  I need to refine some sub-region in the computational domain. To this, I plan to build  some boxes (patches) based on the coarsest level. I am using DM to manage the data. I found there is a new function DMPatachCreate() in the version 3.4.  Is this function the right one I should use for the refined region?  If it is not, which ones I should use?
> 
> That is an experiment and does not work.
>  
>     My proposed approach is to start with  code dm/impls/patch/examples/tests/ex1.c. And then follow the code /dm/examples/tutorials/ex65dm.c. Is this approach the right way to my goal?
> 
>     In addition, I need to use not only the nodes but also the cells including nodes.  Should I use DMMesh to create the cells? I noticed DMMesh is mainly for unstructured grid, but I didn't find other class that implements structured cells.  Can anybody give me some suggestions on multi-level grid or let me know which examples I should start with? Thanks.
> 
> No, that is not appropriate.
> 
> It sounds like you want structured AMR. PETSc does not do this, and there are packages that do it.:
> 
> a) Chombo
> 
> b) SAMRAI
> 
> which are both patch-based AMR. If you want octree-style AMR you could use p4est, but it would mean
> a lot of coding along the lines of http://arxiv.org/abs/1308.1472, or Deal.II which is a complete package.
> I think Deal is the closest to using PETSc solvers.
> 
>   Thanks,
> 
>      Matt
> 
> -- 
> 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

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