$$Date:
2015-10-12 12:00:00 -0600 (Mon, 12 Oct 2015)
$$

Abstract

The Seed_Magnetic_Fields thorn seeds magnetic ﬁelds into an initial hydrodynamic conﬁguration. Currently seeding into TOV stars is supported, according to the poloidal magnetic ﬁeld prescription:

$$\begin{array}{rcll}{A}_{x}& =& -y\ast {A}_{b}\ast pow\left(MAX\left(P-{P}_{c}ut,0.0\right),{n}_{s}\right)& \text{(1)}\text{}\text{}\\ {A}_{y}& =& x\ast {A}_{b}\ast pow\left(MAX\left(P-{P}_{c}ut,0.0\right),{n}_{s}\right)& \text{(2)}\text{}\text{}\\ {A}_{z}& =& 0& \text{(3)}\text{}\text{}\\ Phi& =& 0& \text{(4)}\text{}\text{}\end{array}$$

as speciﬁed in Appendix B of the IllinoisGRMHD code announcement paper:

http://arxiv.org/pdf/1501.07276.pdf

Note that we must be careful if ${A}_{i}$’s are staggered. In this case, the pressure must be interpolated to the staggered point, and the values of $x$ and $y$ must also be shifted.

Both staggered and unstaggered vector potential ﬁelds are currently supported in this thorn.

a_b | Scope: restricted | REAL |

Description: Magnetic ﬁeld strength parameter.
| ||

Range | Default: 1e-3 | |

*:* | Any real
| |

enable_illinoisgrmhd_staggered_a_ﬁelds | Scope: restricted | BOOLEAN |

Description: Deﬁne A ﬁelds on an IllinoisGRMHD staggered grid
| ||

Default: yes | ||

n_s | Scope: restricted | REAL |

Description: Magnetic ﬁeld strength pressure exponent.
| ||

Range | Default: 1.0 | |

*:* | Any real
| |

p_cut | Scope: restricted | REAL |

Description: Cutoﬀ pressure, below which vector potential is set to zero. Typically set to 4% of
the maximum initial pressure.
| ||

Range | Default: 1e-5 | |

0:* | Positive
| |

Implements:

seed_magnetic_ﬁelds

Inherits:

grid

admbase

hydrobase

This section lists all the variables which are assigned storage by thorn WVUThorns/Seed_Magnetic_Fields. 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.

Always: | |

HydroBase::rho[1] | |

HydroBase::press[1] | |

HydroBase::eps[1] | |

HydroBase::vel[1] | |

HydroBase::Bvec[1] | |

HydroBase::Avec[1] | |

HydroBase::Aphi[1] | |

CCTK_INITIAL

seed_magnetic_ﬁelds

set up seed magnetic ﬁeld conﬁguration.

After: | hydrobase_initial | |

Before: | illinoisgrmhd_id_converter | |

Language: | c | |

Type: | function | |