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Chapter T18
TwoPunctures

Author(s): Marcus Ansorg <marcus.ansorg@aei.mpg.de>

Erik Schnetter <schnetter@cct.lsu.edu>

Date: May 18 2004

T18.1 Abstract

T18.2 Introduction

T18.3 Physical System

T18.4 Numerical Implementation

T18.5 Using This Thorn

T18.5.1 Obtaining This Thorn

T18.5.2 Basic Usage

T18.5.3 Special Behaviour

T18.5.4 Interaction With Other Thorns

T18.5.5 Examples

T18.5.6 Support and Feedback

T18.6 History

T18.6.1 Thorn Source Code

T18.6.2 Thorn Documentation

T18.6.3 Acknowledgements

T18.7 Parameters

adm_tol
Scope: restricted   REAL
Description: Tolerance of ADM masses when give_bare_mass=no
Range    Default: 1.0e-10
(0:*)

center_offset
Scope: restricted   REAL
Description: offset b=0 to position (x,y,z)
Range    Default: 0.0
(*:*)

do_initial_debug_output
Scope: restricted   BOOLEAN
Description: Output debug information about initial guess
   Default: no

do_residuum_debug_output
Scope: restricted   BOOLEAN
Description: Output debug information about the residuum
   Default: no

give_bare_mass
Scope: restricted   BOOLEAN
Description: User provides bare masses rather than target ADM masses
   Default: yes

grid_setup_method
Scope: restricted   KEYWORD
Description: How to fill the 3D grid from the spectral grid
Range    Default: Taylor expansion
Taylor expansion
use a Taylor expansion about the nearest collocation point (fast, but might be inaccurate)
evaluation
evaluate using all spectral coefficients (slow)

initial_lapse_psi_exponent
Scope: restricted   REAL
Description: Exponent n for psiˆ- n initial lapse profile
Range    Default: -2.0
(*:*)
Should be negative

keep_u_around
Scope: restricted   BOOLEAN
Description: Keep the variable u around after solving
   Default: no

multiply_old_lapse
Scope: restricted   BOOLEAN
Description: Multiply the old lapse with the new one
   Default: no

newton_maxit
Scope: restricted   INT
Description: Maximum number of Newton iterations
Range    Default: 5
0:*

newton_tol
Scope: restricted   REAL
Description: Tolerance for Newton solver
Range    Default: 1.0e-10
(0:*)

npoints_a
Scope: restricted   INT
Description: Number of coefficients in the compactified radial direction
Range    Default: 30
4:*

npoints_b
Scope: restricted   INT
Description: Number of coefficients in the angular direction
Range    Default: 30
4:*

npoints_phi
Scope: restricted   INT
Description: Number of coefficients in the phi direction
Range    Default: 16
4:*:2

par_b
Scope: restricted   REAL
Description: x coordinate of the m+ puncture
Range    Default: 1.0
(0.0:*)

par_m_minus
Scope: restricted   REAL
Description: mass of the m- puncture
Range    Default: 1.0
0.0:*)

par_m_plus
Scope: restricted   REAL
Description: mass of the m+ puncture
Range    Default: 1.0
0.0:*)

par_p_minus
Scope: restricted   REAL
Description: momentum of the m- puncture
Range    Default: 0.0
(*:*)

par_p_plus
Scope: restricted   REAL
Description: momentum of the m+ puncture
Range    Default: 0.0
(*:*)

par_s_minus
Scope: restricted   REAL
Description: spin of the m- puncture
Range    Default: 0.0
(*:*)

par_s_plus
Scope: restricted   REAL
Description: spin of the m+ puncture
Range    Default: 0.0
(*:*)

rescale_sources
Scope: restricted   BOOLEAN
Description: If sources are used - rescale them after solving?
   Default: yes

schedule_in_admbase_initialdata
Scope: restricted   BOOLEAN
Description: Schedule in (instead of after) ADMBase_InitialData
   Default: yes

solve_momentum_constraint
Scope: restricted   BOOLEAN
Description: Solve for momentum constraint?
   Default: no

swap_xz
Scope: restricted   BOOLEAN
Description: Swap x and z coordinates when interpolating, so that the black holes are separated in the z direction
   Default: no

target_m_minus
Scope: restricted   REAL
Description: target ADM mass for m-
Range    Default: 0.5
0.0:*)

target_m_plus
Scope: restricted   REAL
Description: target ADM mass for m+
Range    Default: 0.5
0.0:*)

tp_epsilon
Scope: restricted   REAL
Description: A small number to smooth out singularities at the puncture locations
Range    Default: 0.0
0:*

tp_extend_radius
Scope: restricted   REAL
Description: Radius of an extended spacetime instead of the puncture
Range    Default: 0.0
0:*
anything positive, should be smaller than the horizon

tp_tiny
Scope: restricted   REAL
Description: Tiny number to avoid nans near or at the pucture locations
Range    Default: 0.0
0:*
anything positive, usually very small

use_external_initial_guess
Scope: restricted   BOOLEAN
Description: Set initial guess by external function?
   Default: no

use_sources
Scope: restricted   BOOLEAN
Description: Use sources?
   Default: no

verbose
Scope: restricted   BOOLEAN
Description: Print screen output while solving
   Default: no

conformal_storage
Scope: shared from STATICCONFORMAL  KEYWORD

T18.8 Interfaces

General

Implements:

twopunctures

Inherits:

admbase

staticconformal

grid

Grid Variables

PRIVATE GROUPS
  Group Names    Variable Names     Details   
puncture_u    compact0
puncture_u    dimensions3
   distributionDEFAULT
   group typeGF
   stagger typeNONE
   tagsprolongation=”none”
   timelevels1
  variable typeREAL
energy    compact0
E    descriptionADM energy of the Bowen-York spacetime
   dimensions0
   distributionCONSTANT
   group typeSCALAR
   stagger typeNONE
   timelevels1
  variable typeREAL
angular_momentum    compact0
J1    descriptionAngular momentum of the Bowen-York spacetime
J2    dimensions0
J3    distributionCONSTANT
   group typeSCALAR
   stagger typeNONE
   timelevels1
  variable typeREAL

PUBLIC GROUPS
  Group Names    Variable Names     Details   
bare_mass    compact0
mp    descriptionBare masses of the punctures
mm    dimensions0
   distributionCONSTANT
   group typeSCALAR
   stagger typeNONE
   timelevels1
  variable typeREAL
puncture_adm_mass    compact0
mp_adm    descriptionADM masses of the punctures (measured at the other spatial infinities)
mm_adm    dimensions0
   distributionCONSTANT
   group typeSCALAR
   stagger typeNONE
   timelevels1
  variable typeREAL

T18.9 Schedule

This section lists all the variables which are assigned storage by thorn EinsteinInitialData/TwoPunctures. Storage can either last for the duration of the run (Always means that if this thorn is activated storage will be assigned, Conditional means that if this thorn is activated storage will be assigned for the duration of the run if some condition is met), or can be turned on for the duration of a schedule function.

Storage

 

 Conditional:
  energy
  angular_momentum
  puncture_adm_mass
  puncture_u bare_mass
   

Scheduled Functions

CCTK_PARAMCHECK (conditional)

  twopunctures_paramcheck

  check parameters and thorn needs

 

 Language:c
 Type: function

ADMBase_InitialData (conditional)

  twopunctures_group

  twopunctures initial data group

 

 Type:group

CCTK_INITIAL (conditional)

  twopunctures_group

  twopunctures initial data group

 

 After: admbase_initialdata
    hydrobase_initial
 Before:admbase_postinitial
   settmunu
   hydrobase_prim2coninitial
 Type: group

TwoPunctures_Group (conditional)

  twopunctures

  create puncture black hole initial data

 

 Language:c
 Storage: puncture_u
   bare_mass
 Type: function

TwoPunctures_Group (conditional)

  twopunctures_metadata

  output twopunctures metadata

 

 After: twopunctures
 Language:c
 Options: global
 Type: function

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