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

Sat Jan 8 12:30:28 CST 2022

Yes I was wondering about different time steps as well because usually
implicit integration moves much faster.
But if it not implemented, then maybe going the « weak coupling » road with
a sub-DM is the way.
Can I ask how you proceed in the rocket engine code you are writing ? IMEX ?

Thibault

Le sam. 8 janv. 2022 à 19:22, Matthew Knepley <knepley at gmail.com> a écrit :

> I do not know how. Right now, composable TS does not work all the way.
>
>   Matt
>
> On Sat, Jan 8, 2022 at 1:03 PM Mark Adams <mfadams at lbl.gov> wrote:
>
>> Can you subcycle with IMEX?
>>
>> On Sat, Jan 8, 2022 at 10:58 AM Matthew Knepley <knepley at gmail.com>
>> wrote:
>>
>>> On Sat, Jan 8, 2022 at 3:05 AM Thibault Bridel-Bertomeu <
>>> thibault.bridelbertomeu at gmail.com> wrote:
>>>
>>>> Le ven. 7 janv. 2022 à 19:45, Thibault Bridel-Bertomeu <
>>>> thibault.bridelbertomeu at gmail.com> a écrit :
>>>>
>>>>> Le ven. 7 janv. 2022 à 19:23, Matthew Knepley <knepley at gmail.com> a
>>>>> écrit :
>>>>>
>>>>>> On Fri, Jan 7, 2022 at 12:58 PM Thibault Bridel-Bertomeu <
>>>>>> thibault.bridelbertomeu at gmail.com> wrote:
>>>>>>
>>>>>>>
>>>>>>> Le ven. 7 janv. 2022 à 14:54, Matthew Knepley <knepley at gmail.com> a
>>>>>>> écrit :
>>>>>>>
>>>>>>>> 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.
>>>>>>>>
>>>>>>>
>>>>>>> Ok then ! Thanks ! I’ll give it a shot and see what happens !
>>>>>>> Setting up the FVM and FEM discretizations will pass by DMSetField
>>>>>>> right ? With a single mesh tagged with two different regions, it should
>>>>>>> show up as two fields, is that correct ?
>>>>>>>
>>>>>>
>>>>>> Yes, the idea is as follows. Each field also has a label argument
>>>>>> that is the support of the field in the domain. Then we create PetscDS
>>>>>> objects for each
>>>>>> separate set of overlapping fields. The current algorithm is not
>>>>>> complete I think, so let me know if this step fails.
>>>>>>
>>>>>
>>>>> Ok, thanks.
>>>>> I’ll let you know and share snippets when I have something started !
>>>>>
>>>>> Talk soon ! Thanks !
>>>>>
>>>>
>>>> Hi Matthew,
>>>>
>>>> I thought about a little something else : what about setting two
>>>> different TS, one for each field of the DM ? Most probably the fluid part
>>>> would be solved with an explicit time stepping whereas the solid part with
>>>> the heat equation would benefit from implicit time stepping. TSSetDM does
>>>> not allow a field specification, is there a way to hack that so that each
>>>> field has its own TS ?
>>>>
>>>
>>> I see at least two options here:
>>>
>>> 1. Split the problems:
>>>
>>>     You can use DMCreateSubDM() to split off part of a problem and use a
>>> solver on that. I have done this for problems with weak coupling.
>>>
>>> 2. Use IMEX
>>>
>>>     For strong coupling, I have used the IMEX TSes in PETSc. You put the
>>> explicit terms in the RHS, and the implicit in the IFunction.
>>>
>>>   Thanks,
>>>
>>>      Matt
>>>
>>>
>>>> Thanks
>>>>
>>>> Thibault
>>>>
>>>>
>>>>> Thibault
>>>>>
>>>>>
>>>>>>   Thanks,
>>>>>>
>>>>>>      Matt
>>>>>>
>>>>>>
>>>>>>> Thanks,
>>>>>>>
>>>>>>> Thibault
>>>>>>>
>>>>>>>
>>>>>>>>   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/>
>>>>>>>>
>>>>>>> --
>>>>>>> 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/>
>>>>>>
>>>>> --
>>>>> 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
>>>>>
>>>> --
>>>> 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/>
>>>
>>
>
> --
> 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
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