On Sat, Jan 8, 2022 at 1:30 PM Thibault Bridel-Bertomeu < thibault.bridelberto...@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 <knep...@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 <mfad...@lbl.gov> wrote: >> >>> Can you subcycle with IMEX? >>> >>> On Sat, Jan 8, 2022 at 10:58 AM Matthew Knepley <knep...@gmail.com> >>> wrote: >>> >>>> On Sat, Jan 8, 2022 at 3:05 AM Thibault Bridel-Bertomeu < >>>> thibault.bridelberto...@gmail.com> wrote: >>>> >>>>> Le ven. 7 janv. 2022 à 19:45, Thibault Bridel-Bertomeu < >>>>> thibault.bridelberto...@gmail.com> a écrit : >>>>> >>>>>> Le ven. 7 janv. 2022 à 19:23, Matthew Knepley <knep...@gmail.com> a >>>>>> écrit : >>>>>> >>>>>>> On Fri, Jan 7, 2022 at 12:58 PM Thibault Bridel-Bertomeu < >>>>>>> thibault.bridelberto...@gmail.com> wrote: >>>>>>> >>>>>>>> >>>>>>>> Le ven. 7 janv. 2022 à 14:54, Matthew Knepley <knep...@gmail.com> >>>>>>>> a écrit : >>>>>>>> >>>>>>>>> On Fri, Jan 7, 2022 at 8:52 AM Thibault Bridel-Bertomeu < >>>>>>>>> thibault.bridelberto...@gmail.com> wrote: >>>>>>>>> >>>>>>>>>> Hi Matthew, >>>>>>>>>> >>>>>>>>>> Le ven. 7 janv. 2022 à 14:44, Matthew Knepley <knep...@gmail.com> >>>>>>>>>> a écrit : >>>>>>>>>> >>>>>>>>>>> On Fri, Jan 7, 2022 at 5:46 AM Thibault Bridel-Bertomeu < >>>>>>>>>>> thibault.bridelberto...@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.bridelberto...@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.bridelberto...@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.bridelberto...@gmail.com >>>>>> >>>>> -- >>>>> Thibault Bridel-Bertomeu >>>>> — >>>>> Eng, MSc, PhD >>>>> Research Engineer >>>>> CEA/CESTA >>>>> 33114 LE BARP >>>>> Tel.: (+33)557046924 >>>>> Mob.: (+33)611025322 >>>>> Mail: thibault.bridelberto...@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.bridelberto...@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/>