[petsc-users] Fluid-Structure interaction with multiple DMPlex
Matthew Knepley
knepley at gmail.com
Sat Jan 8 13:00:43 CST 2022
On Sat, Jan 8, 2022 at 1:30 PM Thibault Bridel-Bertomeu <
thibault.bridelbertomeu at gmail.com> wrote:
> 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
> ?
>
Right now it is IMEX, but we are explicitly substepping particles. Not sure
what the final thing will be.
Thanks,
Matt
> 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
>
--
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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