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

Thibault Bridel-Bertomeu thibault.bridelbertomeu at gmail.com
Sun Jan 9 06:49:23 CST 2022 

Le dim. 9 janv. 2022 à 13:05, Matthew Knepley <knepley at gmail.com> a écrit :

> On Sat, Jan 8, 2022 at 2:13 PM Thibault Bridel-Bertomeu <
> thibault.bridelbertomeu at gmail.com> wrote:
>
>> However if you use IMEX for strong coupling of the two physics solved in
>> each field, then it means you need to write a single set of PDEs that
>> covers everything, don’t you ?
>> If I want to solve Euler equations in one PetscDS and heat equation in
>> the other one, then I need to write a global set of equations to use the
>> IMEX TS , right ?
>>
>
> The way I think about it. You would have explicit terms for Euler, and
> they would also be confined to one part of the domain, but that just
> impacts how you do the residual integral. You do assemble a combined
> residual for all dogs, however, which I think is what you mean.
>

Hmm I'm not quite sure yet, probably because I haven't really started
implementing it and I am not familiar with finite elements in PETSc.
The way I see it is that a TS expects to be solving dU/dt = F, that's why
I'm imagining that even with two domains with two different physics, one
has to write the problem under the previous form. And when it comes to a
FVM version of Euler + a FEM version of heat eqn, I'm not quite certain how
to write it like that.
Am I making any sense ? ô_o

Thanks,
Thibault


>   Thanks,
>
>     Matt
>
>
>> Thanks,
>>
>> Thibault
>>
>> Le sam. 8 janv. 2022 à 20:00, Matthew Knepley <knepley at gmail.com> a
>> écrit :
>>
>>> 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/>
>>>
>> --
>> 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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