[Users] Issue with thorn Trigger

[Lorenzo Ennoggi]

Dear Erik,
thank you very much. I am now trying the way Frank suggested before and, if
again the finest refinement level does not get enlarged, I will probably
try to edit the checkpoint files.

Sincerely,
Lorenzo

Il giorno lun 14 giu 2021 alle ore 15:45 Erik Schnetter <
schnetter at cct.lsu.edu> ha scritto:

> On Mon, Jun 14, 2021 at 5:45 AM Lorenzo Ennoggi
> <lorenzo.ennoggi at gmail.com> wrote:
> >
> > Dear all,
> > I would like to restart a simulation from a checkpoint enlarging the
> finest refinement level in my grid. In particular, I would like to change
> CarpetRegrid2::radius_1[5] = 20.1 to CarpetRegrid2::radius_1[5] = 25. I
> tried to do that by making the parameter CarpetRegrid2::radius_1 always
> steerable and adding the following lines to my parameter file:
> >
> >
> > ActiveThorns                                = "Trigger"
> > Trigger::Trigger_Number                     = 1
> >
> > Trigger::Trigger_Checked_Variable[0]        = "hydrobase::rho"
> > Trigger::Trigger_Relation[0]                = ">"
> > Trigger::Trigger_Checked_Value[0]           = 1.e-4
> > Trigger::Trigger_Reduction[0]               = "maximum"
> >
> > Trigger::Trigger_Reaction[0]                = "steerparam"
> > Trigger::Trigger_Steered_Parameter_Thorn[0] = "CarpetRegrid2"
> > Trigger::Trigger_Steered_Parameter_Name[0]  = "radius_1[5]"
> > Trigger::Trigger_Steered_Parameter_Value[0] = "25." #New value of the
> above parameter
> > Trigger::Trigger_Once[0]                    = 1     #It means "yes"
> > Trigger::Trigger_Debug                      = 1     #It means "yes"
> >
> >
> > In this way, the trigger should act immediately, as the maximum of rho
> is ~1e-3 in my case. Indeed, it looks like the trigger is working fine, as
> the standard output says
> >
> > [...]
> > INFO (Trigger): Testing triggers
> > INFO (Trigger): last_checked: -1
> > INFO (Trigger): reducing trigger 0 red_handle 2 varindex 428
> > INFO (Trigger): reducing was ok
> > INFO (Trigger): trigger nr. 0 fullfilled for rho (0.000804>0.000100)
> > INFO (Trigger): Steering parameter
> > INFO (Trigger): Parameter steered
> > [...]
> >
> > but unfortunately, looking at the 2D output with VisIt, the finest
> refinement level does not get enlarged (i.e. radius_1[5] does not appear to
> have been steered at all). Do you have any suggestions on how to get this
> trigger to work? Or, are you aware of other ways of obtaining the same
> result without using the thorn Trigger?
>
> Changing these parameters has no effect, even if they were steerable.
>
> CarpetRegrid2 uses these parameters to set up the initial grid
> structure, by setting the grid scalars "positions", "radius", etc.
> During regridding, only these grid scalars are examined; the
> parameters are ignored. Other mechanisms to update the grid structure
> (e.g. by tracking horizons or punctures) update these grid scalars,
> which then determines the grid structure during regridding. These grid
> scalars are checkpointed and recovered, as all grid variables are.
>
> To modify the grid structure you need to modify these grid scalars.
> You can do this e.g. via Python by doing surgery on the checkpoint
> files, or by scheduling a function that runs right after recovery.
> Carpet performs a regridding step after recovering, before the first
> evolution step.
>
> -erik
>
> --
> Erik Schnetter <schnetter at cct.lsu.edu>
> http://www.perimeterinstitute.ca/personal/eschnetter/
>
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