[Users] Issue with thorn Trigger

[Roland Haas]

Hello Lorenzo,

in both the method Frank suggested and the one Erik suggested, the
change will only take place at the next regrid
(CarpetRegrid2::regrid_every or so) so you may also want to steer that
parameter to 1 or so to force an immediate (well almost, I guess it
could be 1 step) regrid (dangerous though since the steered parameter
stays 1 until you steer it back to its original value).

Yours,
Roland

> 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>
> > https://urldefense.com/v3/__http://www.perimeterinstitute.ca/personal/eschnetter/__;!!DZ3fjg!qYoVTmqqjvpe7SdEbhr3oXsKHin8WUOlbL3xDphyw_CYTyL0-X5jNHlBTuZC4lTn$ 
> >  


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