[Users] AHFinderDirect test in cosmology

[Miguel Zilhão]

hi Luciano,

we've done something like this in https://arxiv.org/abs/1204.2019
you can indeed find cosmological apparent horizons using AHFinderDirect, the trick is to add the 
following parameter:

AHFinderDirect::surface_definition[1]   = "inner expansion"

hope this helps.

cheers,
Miguel

On 23/07/2022 06:48, Luciano Combi wrote:
> Hi all,
> 
> I'm trying to use AHFinderDirect to find the apparent horizon in the de Sitter metric, implemented 
> in the Exact thorn in comoving coordinates. I tried a few things but cannot get it to work. Have 
> someone tried something similar, i.e. using the AHFD in cosmological spacetimes instead of BHs? 
> Below I attach a typical parfile I used
> 
> Thanks!
> -------------------------------------------------------
> # flesh
> cactus::cctk_itlast = 0
> 
> ActiveThorns = "PUGH"
> driver::ghost_size = 3
> driver::global_nx = 120
> driver::global_ny = 120
> driver::global_nz = 120 ##57
> 
> ActiveThorns = "CoordBase SymBase CartGrid3D"
> grid::avoid_origin = "false"
> grid::type = "byspacing"
> grid::dxyz = 0.2
> 
> ActiveThorns = "ADMBase ADMCoupling StaticConformal CoordGauge SpaceMask Exact"
> ADMBase::initial_lapse = "exact"
> ADMBase::initial_shift = "exact"
> ADMBase::initial_data = "exact"
> ADMBase::lapse_evolution_method = "exact"
> ADMBase::shift_evolution_method = "exact"
> ADMBase::metric_type = "physical"
> Exact::exact_model = "de Sitter+Lambda"
> Exact::de_Sitter_Lambda__scale = 0.50
> 
> 
> ########################################
> 
> ActiveThorns = "IOUtil"
> IOUtil::parfile_write = "no"
> 
> ########################################
> 
> ActiveThorns = "AEILocalInterp PUGHInterp PUGHReduce SphericalSurface AHFinderDirect"
> 
> AHFinderDirect::print_timing_stats = "true"
> 
> AHFinderDirect::output_Theta_every = 1
> AHFinderDirect::h_base_file_name     = "dS.h"
> AHFinderDirect::Theta_base_file_name = "dS.Theta"
> 
> AHFinderDirect::N_horizons = 1
> AHFinderDirect::origin_x[1] = 0.0
> AHFinderDirect::origin_y[1] = 0.0
> AHFinderDirect::origin_z[1] = 0.0
> 
> AHFinderDirect::initial_guess_method[1] = "coordinate sphere"
> AHFinderDirect::initial_guess__coord_sphere__x_center[1] =  0.0
> AHFinderDirect::initial_guess__coord_sphere__y_center[1] =  0.0
> AHFinderDirect::initial_guess__coord_sphere__z_center[1] =  0.0
> AHFinderDirect::initial_guess__coord_sphere__radius[1] = 1.0
> ------------------------
> -- 
> *Luc Combi*
> CONICET PhD fellow (Buenos Aires, Argentina)
> Instituto Argentino de Radioastronomía
> 
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