TwoPunctures

Marcus Ansorg <marcus.ansorg@aei.mpg.de>
Erik Schnetter <schnetter@cct.lsu.edu>

May 18 2004

Abstract

1 Introduction

2 Physical System

3 Numerical Implementation

4 Using This Thorn

4.1 Obtaining This Thorn

4.2 Basic Usage

4.3 Special Behaviour

4.4 Interaction With Other Thorns

4.5 Examples

4.6 Support and Feedback

5 History

5.1 Thorn Source Code

5.2 Thorn Documentation

5.3 Acknowledgements

References

6 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 STATICCONFORMALKEYWORD

7 Interfaces

General

Implements:

twopunctures

Inherits:

admbase

staticconformal

grid

Grid Variables

7.0.1 PRIVATE GROUPS

  Group Names     Variable Names   Details    
puncture_u puncture_u compact 0
dimensions 3
distribution DEFAULT
group type GF
tags prolongation=”none”
timelevels 1
variable type REAL
energy compact 0
E description ADM energy of the Bowen-York spacetime
dimensions 0
distribution CONSTANT
group type SCALAR
timelevels 1
variable type REAL
angular_momentum compact 0
J1 description Angular momentum of the Bowen-York spacetime
J2 dimensions 0
J3 distribution CONSTANT
group type SCALAR
timelevels 1
variable type REAL

7.0.2 PUBLIC GROUPS

  Group Names     Variable Names   Details    
bare_mass compact 0
mp description Bare masses of the punctures
mm dimensions 0
distribution CONSTANT
group type SCALAR
timelevels 1
variable type REAL
puncture_adm_mass compact 0
mp_adm description ADM masses of the punctures (measured at the other spatial infinities)
mm_adm dimensions 0
distribution CONSTANT
group type SCALAR
timelevels 1
variable type REAL

8 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 bare_mass
  puncture_u
   

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
  Reads: grid::coordinates(everywhere)
  Storage: puncture_u
  Type: function
  Writes: twopunctures::mp(everywhere)
    twopunctures::mm(everywhere)
    twopunctures::mp_adm(everywhere)
    twopunctures::mm_adm(everywhere)
    twopunctures::e(everywhere)
    twopunctures::j1(everywhere)
    twopunctures::j2(everywhere)
    twopunctures::j3(everywhere)
    twopunctures::puncture_u(everywhere)
    staticconformal::conformal_state(everywhere)
    staticconformal::confac_2derivs(everywhere)
    staticconformal::confac_1derivs(everywhere)
    staticconformal::confac(everywhere)
    admbase::alp(everywhere)
    admbase::metric(everywhere)
    admbase::curv(everywhere)

TwoPunctures_Group (conditional)

  twopunctures_metadata

  output twopunctures metadata

 

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