Maria, I do not track the centers of the stars in the AHFinderDirect, but in case of a strong kick in the post-merger remnant that could be useful since the BH may form far from the origin.
I always looked for two horizons with two different initial guesses in order to be sure to find at least 1 solution for the AH. It is not necessary though.
Cheers, Bruno
Il giorno mer 21 apr 2021 alle ore 22:13 Hamilton, Maria < babiuc@marshall.edu> ha scritto:
Bruno,
Awesome! Thank you for sharing! I'll give it a try! 🙂 Just a quick question: so, there is no need to "track_origin"? Also, although we expect only one merged black hole, would it be necessary to set "n_horizons = 2" ?
Maria
*Maria C. Babiuc Hamilton, Ph.D.* *Professor, Department of Physics * *College of Science, **Marshall University,* *1 John Marshall Drive, **Huntington, WV, 25755*
*Room S 257, Phone: (304)696-2754 *
*From:* Bruno Giacomazzo bruno.giacomazzo@unimib.it *Sent:* Wednesday, April 21, 2021 5:12 AM *To:* Erik Schnetter schnetter@cct.lsu.edu *Cc:* Hamilton, Maria babiuc@marshall.edu; users@einsteintoolkit.org < users@einsteintoolkit.org> *Subject:* Re: [Users] Assertion `ox' failed
x=0 is OK since in a BNS system the BH will form at the origin where the NSs merge (unless there is a kick). These are the parameters I use in my BNS runs:
#------------------ahfinderdirect----------------------------------------------
ahfinderdirect::find_after_individual_time[1] = 2000 ahfinderdirect::find_after_individual_time[2] = 2000 ahfinderdirect::find_every = 64 ahfinderdirect::geometry_interpolator_name = "Lagrange polynomial interpolation" ahfinderdirect::geometry_interpolator_pars = "order=4" ahfinderdirect::initial_guess__coord_sphere__radius[1] = 1 ahfinderdirect::initial_guess__coord_sphere__radius[2] = 3 ahfinderdirect::mask_buffer_thickness = 0 ahfinderdirect::mask_radius_multiplier = 0.6 ahfinderdirect::mask_radius_offset = 0 ahfinderdirect::max_allowable_horizon_radius[1] = 15 ahfinderdirect::max_allowable_horizon_radius[2] = 15 ahfinderdirect::max_allowable_theta_growth_iterations = 10 ahfinderdirect::max_allowable_theta_nonshrink_iterations = 10 ahfinderdirect::max_newton_iterations__initial = 50 ahfinderdirect::max_newton_iterations__subsequent = 50 ahfinderdirect::move_origins = yes ahfinderdirect::n_horizons = 2
ahfinderdirect::origin_x[1] = 0 ahfinderdirect::origin_x[2] = 0 ahfinderdirect::output_h_every = 64 ahfinderdirect::predict_origin_movement = yes ahfinderdirect::reset_horizon_after_not_finding[1] = no ahfinderdirect::reset_horizon_after_not_finding[2] = no ahfinderdirect::reshape_while_moving = yes
ahfinderdirect::surface_interpolator_name = "Lagrange polynomial interpolation" ahfinderdirect::surface_interpolator_pars = "order=4" ahfinderdirect::verbose_level = "physics details" ahfinderdirect::which_surface_to_store_info[1] = 0 ahfinderdirect::which_surface_to_store_info[2] = 1
Il giorno mar 20 apr 2021 alle ore 19:30 Erik Schnetter < schnetter@cct.lsu.edu> ha scritto:
Maria
I see that you only set up one horizon. You need to set at least N_horizons to 2. All parameters that you set for horizon one (those with array index [1]), will also need to be set for the second horizons. It's also weird that the horizon is at x=0; in a binary system, I'd expect it to be away from the origin.
You probably want to set AHFinderDirect::which_surface_to_store_info[2] = 1 to store information about the second horizon in a different spherical surface.
-erik
On Tue, Apr 20, 2021 at 12:56 PM Hamilton, Maria babiuc@marshall.edu wrote:
Hello,
Could I please get some help in activating the horizon finder correctly
in a bns run?
This is what I have in the par file:
ActiveThorns = "AHFinderDirect" AHFinderDirect::find_after_individual_time[1] = 1500 AHFinderDirect::find_every = 64 AHFinderDirect::output_h_every = 128
AHFinderDirect::geometry_interpolator_name = "Lagrange polynomial
interpolation"
AHFinderDirect::geometry_interpolator_pars = "order=4" AHFinderDirect::surface_interpolator_name = "Lagrange polynomial
interpolation"
AHFinderDirect::surface_interpolator_pars = "order=4" AHFinderDirect::which_surface_to_store_info[1] = 0
AHFinderDirect::initial_guess_method [1] = "coordinate sphere" AHFinderDirect::initial_guess__coord_sphere__radius[1] = 0.3 AHFinderDirect::initial_guess__coord_sphere__x_center[1] = 0.0
AHFinderDirect::N_horizons = 1 AHFinderDirect::max_allowable_horizon_radius[1] = 3 AHFinderDirect::reset_horizon_after_not_finding[1] = "no"
AHFinderDirect::origin_x[1] = 0 AHFinderDirect::move_origins = "yes" AHFinderDirect::predict_origin_movement = "yes" AHFinderDirect::reshape_while_moving = "yes"
AHFinderDirect::track_origin_from_grid_scalar[1] = "yes" AHFinderDirect::track_origin_source_x[1] =
"Hydro_Analysis::Hydro_Analysis_rho_max_loc[0]"
AHFinderDirect::track_origin_source_y[1] =
"Hydro_Analysis::Hydro_Analysis_rho_max_loc[1]"
AHFinderDirect::track_origin_source_z[1] =
"Hydro_Analysis::Hydro_Analysis_rho_max_loc[2]"
AHFinderDirect::track_origin_from_grid_scalar[2] = "yes" AHFinderDirect::track_origin_source_x[2] =
"Hydro_Analysis::Hydro_Analysis_rho_max_loc[0]"
AHFinderDirect::track_origin_source_y[2] =
"Hydro_Analysis::Hydro_Analysis_rho_max_loc[1]"
AHFinderDirect::track_origin_source_z[2] =
"Hydro_Analysis::Hydro_Analysis_rho_max_loc[2]"
And this is what happens when is activated:
cactus_bns:
/home/babiuc/ET_2020_11/Cactus/configs/bns/build/AHFinderDirect/driver/Newton.cc:109: void AHFinderDirect::track_origin(const cGH*, AHFinderDirect::patch_system&, AHFinderDirect::AH_data*, int, bool): Assertion `ox' failed.
Rank 0 with PID 22304 received signal 6 Writing backtrace to BNS_BSSN_Sly_myAHF_dx12/backtrace.0.txt
Primary job terminated normally, but 1 process returned a non-zero exit code. Per user-direction, the job has been aborted.
thanks, Maria _______________________ Maria C. Babiuc Hamilton, Ph.D. Professor, Department of Physics College of Science, Marshall University, 1 John Marshall Drive, Huntington, WV, 25755 Room S 257, Phone: (304)696-2754
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