[Users] Grid structure inconsistency & errors in surface mask locations

Konrad Topolski k.topolski2 at student.uw.edu.pl
Mon Apr 19 09:38:47 CDT 2021

I have been trying a variety of initial guesses, but to no avail.

The setup is, in short:
par_b = 3.0
target_m_plus = 0.25
target_m_minus = 0.75

And the smaller black hole's apparent horizon gets detected easily, which
cannot be said of the bigger one. My estimates for the AHFinderDirect were
at -1.05 to -0.95 for the center of the ellipsoid/sphere, with initial
guesses for the x_radius ranging from 0.25 to 0.4, with y_radius, z _radius
about 10-20% smaller.

Am I still not getting enough resolution? The refinement levels in my
finest setup around x=-1 are:

Carpet::max_refinement_levels    =8
CarpetRegrid2::movement_threshold_1 =   0.16
CarpetRegrid2::num_levels_2         =  8
CarpetRegrid2::position_x_2         = -1.0
CarpetRegrid2::radius_2[ 1]         =  64.0
CarpetRegrid2::radius_2[ 2]         =  16.0
CarpetRegrid2::radius_2[ 3]         =   8.0
CarpetRegrid2::radius_2[ 4]         =   4.0
CarpetRegrid2::radius_2[ 5]         =   3.0
CarpetRegrid2::radius_2[ 6]         =   2.5
CarpetRegrid2::radius_2[ 7]         =   2.0
CarpetRegrid2::movement_threshold_2 =   0.16

I do not know a-priori if this apparent horizon is best approximated by an
ellipsoid (can one see this before performing the numerical simulation?) or
not, but I don't know if I'm on the right track.
It seems weird to me that I cannot find the x=-1 AH, even though the
corresponding black hole it is ~3 times more massive.

In another attempt, I tried to copy the philosophy of the setup in the
GW150914.rpar file,
setting the center_offset for the two punctures and other parameters, but
that didn't work either.
I took
target_mp=0.75, target_mm=0.25,
separation D=6, so xp=D*mm = 1.5, xm=D*mp=-4.5,
par_b=D/2 = 3.0, center_offset=xp-half_D=-1.5
(all here:
I'm starting to doubt if any of these setups is correct.

By the way, can I somehow redirect the outputs of all MPI processes to one
file at real time, better still, override the creation of CCTK_Proc files

Best regards
Konrad Topolski
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