[petsc-users] issues with VecSetValues in petsc 3.19

[Matthew Knepley]

On Thu, Apr 20, 2023 at 11:07 AM Edoardo alinovi <edoardo.alinovi at gmail.com>
wrote:

> Hi Matt,
>
> thanks for sharing the literature.
>
> Would you suggest any monolitic approach for the mpiaij/mpibaij matrix
> instead of fieldsplit?
>

I have not seen them be better, but Vanka-type smoothers can work for this
system.


> I did some blind search using gamg/hypre and they look terribile. I guess
> i am missing a trick, probaly they are not the way to go?
>

I believe that trick is that the patches you use have to very specific.

  Thanks,

     Matt


> Thanks!
>
> Il Lun 17 Apr 2023, 13:50 Matthew Knepley <knepley at gmail.com> ha scritto:
>
>> On Mon, Apr 17, 2023 at 6:37 AM Edoardo alinovi <
>> edoardo.alinovi at gmail.com> wrote:
>>
>>> Sure thing, the solver I am working on is this one:
>>> https://gitlab.com/alie89/flubio-code-fvm.
>>>
>>> It is a 3D, collocated, unstructured, finite volume solver for
>>> incompressibility NS. I can run steady, unsteady and I can use SIMPLE, PISO
>>> and Factional step method (both explicit and fully implicit momentum). I
>>> can also solve for turbulence (k-omega, BSL, SST, Spalart-Allmars, LES). I
>>> have also implemented some kind of Immersed boundary (2D/3D) that I need to
>>> resume at some point.
>>>
>>> Hot topic of the moment, I am developing a fully coupled pressure based
>>> solver using field-split. What I have now is working ok, I have validated
>>> it on a lot of 2D problems and going on with 3D right now.  If all the
>>> tests are passed, I'll focus on tuning the field splitting which looks to
>>> be a quite interesting topic!
>>>
>>
>> I think a very good discussion of the issues from the point of view of
>> FEM is
>>
>>    https://arxiv.org/abs/1810.03315
>>
>> There should be a similar analysis from the FVM side, although it might
>> not be possible to
>> find a pressure discretization compatible with the FVM velocity for this
>> purpose.
>>
>>   Thanks,
>>
>>      Matt
>>
>>
>>> Flubio is a project I have been carrying on since PhD days. The
>>> implementation is 99% on my shoulders, despite the fact I am
>>> collaborating with some people around. I am coding evenings and
>>> weekends/free time, it gives me a lot of satisfaction and also a lot of
>>> insights!
>>>
>>
>> --
>> 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
>>
>> https://www.cse.buffalo.edu/~knepley/
>> <http://www.cse.buffalo.edu/~knepley/>
>>
>

-- 
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

https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
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