[petsc-users] Fluid-Structure interaction with multiple DMPlex

[Matthew Knepley]

On Fri, Jan 7, 2022 at 8:52 AM Thibault Bridel-Bertomeu <
thibault.bridelbertomeu at gmail.com> wrote:

> Hi Matthew,
>
> Le ven. 7 janv. 2022 à 14:44, Matthew Knepley <knepley at gmail.com> a
> écrit :
>
>> On Fri, Jan 7, 2022 at 5:46 AM Thibault Bridel-Bertomeu <
>> thibault.bridelbertomeu at gmail.com> wrote:
>>
>>> Dear all,
>>>
>>> First of, happy new year everyone !! All the best !
>>>
>>
>> Happy New Year!
>>
>>
>>> I am starting to draft a new project that will be about fluid-structure
>>> interaction: in particular, the idea is to compute the Navier-Stokes (or
>>> Euler nevermind) flow around an object and _at the same time_ compute the
>>> heat equation inside the object.
>>> So basically, I am thinking a mesh of the fluid and a mesh of the
>>> object, both meshes being linked at the fluid - solid interface.
>>>
>>
>> First question: Are these meshes intended to match on the interface? If
>> not, this sounds like overset grids or immersed boundary/interface methods.
>> In this case, more than one mesh makes sense to me. If they are intended to
>> match, then I would advocate a single mesh with multiple problems defined
>> on it. I have experimented with this, for example see SNES ex23 where I
>> have a field in only part of the domain. I have a large project to do
>> exactly this in a rocket engine now.
>>
>
> Yes the way I see it is more of a single mesh with two distinct regions to
> distinguish between the fluid and the solid. I was talking about two meshes
> to try and explain my vision but it seems like it was unclear.
> Imagine if you wish a rectangular box with a sphere inclusion: the sphere
> would be tagged as a solid and the rest of the domain as fluid. Using Gmsh
> volumes for instance.
> Ill check out the SNES example ! Thanks !
>
>
>>
>>> First (Matthew maybe ?) do you think it is something that could be done
>>> using two DMPlex's that would somehow be spawned from reading a Gmsh mesh
>>> with two volumes ?
>>>
>>
>> You can take a mesh and filter out part of it with DMPlexFilter(). That
>> is not used much so I may have to fix it to do what you want, but that
>> should be easy.
>>
>>
>>> And on one DMPlex we would have finite volume for the fluid, on the
>>> other finite elements for the heat eqn ?
>>>
>>
>> I have done this exact thing on a single mesh. It should be no harder on
>> two meshes if you go that route.
>>
>>
>>> Second, is it something that anyone in the community has ever imagined
>>> doing with PETSc DMPlex's ?
>>>
>>
>> Yes, I had a combined FV+FEM simulation of magma dynamics (I should make
>> it an example), and currently we are doing FVM+FEM for simulation of a
>> rocket engine.
>>
>
> Wow so it seems like it’s the exact same thing I would like to achieve as
> the rocket engine example.
> So you have a single mesh and two regions tagged differently, and you use
> the DmPlexFilter to solve FVM and FEM separately ?
>

With a single mesh, you do not even need DMPlexFilter. You just use the
labels that Gmsh gives you. I think we should be able to get it going in a
straightforward way.

  Thanks,

     Matt


> Thanks !
>
> Thibault
>
>
>>   Thanks,
>>
>>      Matt
>>
>>
>>> As I said it is very prospective, I just wanted to have your opinion !!
>>>
>>> Thanks very much in advance everyone !!
>>>
>>> Cheers,
>>> Thibault
>>>
>>>
>>
>> --
>> 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/>
>>
> --
> Thibault Bridel-Bertomeu
> —
> Eng, MSc, PhD
> Research Engineer
> CEA/CESTA
> 33114 LE BARP
> Tel.: (+33)557046924
> Mob.: (+33)611025322
> Mail: thibault.bridelbertomeu at gmail.com
>


-- 
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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