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

[Thibault Bridel-Bertomeu]

Hello everybody,

So, let's say i have the mesh attached to this email that has 2 physical
surfaces and 5 physical curves. This gives me 2 strata in the "Cell Sets"
and 5 strata in the "Face Sets".
Would something like the following piece of code be the right way to
"extract" and manipulate each stratum of the "Cell Sets" to assign them a
DS, a TS etc...?

    DMLabel surfacesLabel;    ierr = DMGetLabel(dm, "Cell Sets",
&surfacesLabel);CHKERRQ(ierr);    IS fluidIS;    ierr =
DMLabelGetStratumIS(surfacesLabel, 2, &fluidIS);CHKERRQ(ierr);
DMLabel fluidLabel;    ierr = DMLabelCreate(PETSC_COMM_WORLD, "Fluid",
&fluidLabel);CHKERRQ(ierr);    ierr = DMLabelSetStratumIS(fluidLabel,
1, fluidIS);CHKERRQ(ierr);

Once I have the Fluid label linked to the fluidIS (same for the
solid), should I call DMPlexLabelComplete on both the labels before
proceeding and calling the DMCreateSubDM with their IS ?

Thanks,

Thibault

Le dim. 9 janv. 2022 à 23:04, Jed Brown <jed at jedbrown.org> a écrit :

> Thibault Bridel-Bertomeu <thibault.bridelbertomeu at gmail.com> writes:
>
> > 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 ?
>
> Yes.
>
> You can use multirate integrators, which are like subcycling while
> controlling splitting error. Most subcycling approaches will limit your
> global convergence to first order in time. First order with a very small
> coefficient ("weak coupling") might be okay, but you do need to quantify it
> for each physical regime and resolution.
>
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