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

Sat Jan 8 12:03:01 CST 2022

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/>
>
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