[petsc-users] Detecting steady-state with TS

[Mark Adams]

You could add a
https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/TS/TSMonitorSet.html
method, compute the time derived and decide how to declare converged.

Then set converged (
https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/TS/TSSetConvergedReason.html)
with TS_CONVERGED_USER

That should cause TS to wrap up the solve and exit cleanly.

Mark


On Thu, Apr 29, 2021 at 3:27 PM Salazar De Troya, Miguel via petsc-users <
petsc-users at mcs.anl.gov> wrote:

> I am solving the signed distance equation
>
>
>
> \frac{\partial \phi}{\partial t} + sign (\phi_{0})(|\nabla \phi| - 1) = 0
>
>
>
> using a Local Discontinuous Galerkin (LDG) method as described in
> https://www.sciencedirect.com/science/article/pii/S0021999110005255
>
>
>
> I am interested in solving it close to steady state. I was hoping I could
> measure how close to steady state the solution is by using the
> TSSetEventHandler infrastructure, but the handler does not have information
> on the time derivative. I looked at TSPSEUDO, but it forces me to use an
> implicit method, which I cannot provide because how the LDG method works
> (it calculates the fluxes solving additional equations). This makes me
> wonder if the LDG method is the best choice, so I am open to suggestions.
>
>
>
> Given my current progress with the LDG approach, I am wondering if there
> is a way to solve to steady state using explicit algorithms such as
> Runge-Kutta.
>
>
>
> Thanks
>
> Miguel
>
>
>
> Miguel A. Salazar de Troya
>
> Postdoctoral Researcher, Lawrence Livermore National Laboratory
>
> B141
>
> Rm: 1085-5
>
> Ph: 1(925) 422-6411
>
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