[Users] Problem regriding using trigger thorn
rhaas at illinois.edu
Sun May 1 14:54:02 CDT 2022
At runtime you have to steer the grid scalars in CarpetRegrid2 rather
than the parameters.
See the gallery example for hmns:
Trigger::Trigger_Steered_Scalar  = "CarpetRegrid2::num_levels" # == num_levels_1
Trigger::Trigger_Steered_Scalar_Value = "1"
and for the radii you can look up the Regrid2 docs
from its interface.ccl (center = 0 in your case for radius_1).
You also must set Trigger::Trigger_Steered_Scalar_Index[triggernum] to
the level needed (6 in your case).
> I am running a simulation with Daniel Siegel where we use a base level
> plus 6 refinement levels, like the following:
> CarpetRegrid2::radius_1 = 336.0 # dx/64
> CarpetRegrid2::radius_1 = 168.0 # dx/64
> CarpetRegrid2::radius_1 = 84.0 # dx/64
> CarpetRegrid2::radius_1 = 42.0 # dx/64
> CarpetRegrid2::radius_1 = 21.0 # dx/64
> CarpetRegrid2::radius_1 = 10.5 # dx/64
> We ran simulations of a neutrino-driven wind from a Neutron star, out
> to ~150 ms, and now we want to turn on a high magnetic field. We have
> tried B-fields of varying strengths, but if we try a B-field strength
> that is too high, we find errors generated on the innermost refinement
> level boundary. We believe if we enlarge the innermost box size ie.
> CarpetRegrid2::radius_1 = 10.5 --> ~19-20, these errors would
> disappear. But we are having trouble doing this. In our attempt, we
> activate the trigger thorn with the following settings:
> ActiveThorns = "Trigger"
> Trigger::Trigger_Debug = 1
> Trigger::Trigger_Number =1
> Trigger::Trigger_Reduction =""
> Trigger::Trigger_Relation ="<"
> Trigger::Trigger_Checked_Value = 1.1
> Trigger::Trigger_Reaction ="steerparam"
> Trigger::Trigger_Steered_Parameter_Value  = "19.32"
> Trigger::Trigger_Steered_Parameter_Name  = "radius_1"
> Trigger::Trigger_Steered_Parameter_Thorn  = "CarpetRegrid2"
> (We use a trivially satisfied trigger condition so that the parameter
> value is reset immediately upon restart.)
> Since the CarpetRegrid2 variable "radius_1" is not steerable, we
> had to modify this to make it such. After turning debug on, we see the
> following output:
> INFO (Trigger): Testing triggers
> INFO (Trigger): last_checked: -1
> INFO (Trigger): trigger nr. 0 fulfilled for GRHydro_rho_min
> INFO (Trigger): Steering parameter
> INFO (Trigger): Parameter steered
> Which supposedly successfully resets the value correctly. We believe
> that even though this may be the case, the actual grid is not
> changing. We plot the first 2 boundary levels and show them in the
> attached file.
> There must be interpolation of the second innermost grid onto the
> innermost grid, and we believe this is not actually handled
> mid-simulation and thus doesn't not result in the change we expect.
> Is there any simple way of changing the inner grid easily?
> Any help is much appreciated!
> [image: image(1).png]
> Dhruv Desai
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