[petsc-users] Domain Decomposition Method for Parallel FEM Code

[Hanglin Ye]

Hi,
Thank you again for the reply. I am trying to run ex62. But there is an
error :  "Mesh generation needs external package support. Please
reconfigure with --download-triangle." I then configure again with
--download triangle, and it is download and installed. But this error keeps
showing up. Could you please let me know if I am missing anything?
Thank you.

On Wed, Feb 11, 2015 at 1:05 PM, Matthew Knepley <knepley at gmail.com> wrote:

> On Wed, Feb 11, 2015 at 12:01 PM, Hanglin Ye <hanglinye at gmail.com> wrote:
>
>> Thank you very much for the reply.
>>
>> I am not very sure if structured/unstructured mesh means differently in
>> PETSc, but my mesh are simply hexahedral mesh, which I assume is
>> structured. Is there any difference when dealing with structured and
>> unstructured mesh?
>>
>
>
>> And another question is: Can I say that I only need to provide the whole
>> domain, and PETSc can take care of the decomposition, so that I do not need
>> to use software such as Metis to partition the mesh in advance?
>>
>
> Now your mesh sounds unstructured. SNES ex62 is an example of a finite
> element code using DMPlex
> which can have tetrahedral or hexahedral cells, and solves Stokes equation.
>
> PETSc can handle partitioning and distribution for you.
>
>   Thanks,
>
>     Matt
>
>
>> Thank you.
>>
>>
>> On Feb 11, 2015, at 12:01, Matthew Knepley <knepley at gmail.com> wrote:
>>
>> On Wed, Feb 11, 2015 at 10:52 AM, Hanglin Ye <hanglinye at gmail.com> wrote:
>>
>>> Dear all,
>>>
>>> I am new to PETSc and I want to use it to parallel my current serial FEM
>>> code. I want to use Domain Decomposition Method so that the whole FEM
>>> domain is partitioned into sub-domains and computations are performed in
>>> sub-domains then assemble together. Is there a way to use PETSc to realize
>>> that ?
>>>
>>> I've been searching through tutorials but none seems to be clear about
>>> this aspect. I mainly wish to know what solver of PETSc do I need.
>>>
>>
>> Do you have a structured or unstructured mesh? In either case, you will
>> use a DM to encapsulate your mesh, which will give you
>> DMLocalToGlobal() and DMGlobalToLocal() to map between Vecs which are
>> appropriate for the solver (global) and those with
>> ghost regions which are appropriate for assembly (local). You can see an
>> example in SNES ex5, ex12, and ex19.
>>
>>  Thanks,
>>
>>    Matt
>>
>>
>>> Thank you very much.
>>> --
>>> Hanglin Ye
>>> Ph.D.Student MANE, RPI
>>>
>>
>>
>>
>> --
>> 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
>>
>>
>
>
> --
> 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
>



-- 
Hanglin Ye
Ph.D.Student MANE, RPI
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