Vacuum Spacetimes
Evolution of vacuum spacetime is provided by the McLachlan code. McLachlan solves the Einstein vacuum equations in 3D Cartesian coordinates using adaptive mesh refinement
and can be combined with matter codes for modeling spacetimes containing matter. McLachlan is implemented using the Kranc package. Features of McLachlan include:
- complete implementation of the BSSNOK general relativity spacetime evolution equations including all the standard tricks that ensures stability
- up-winding for the shift advection terms
- standard moving puncture Gamma-driver and 1 + log gauges
- phi- and W- methods
- static and radiative outer boundary conditions
- inclusion of matter through the TmunuBase interface
- up to 8th order finite differencing
- OpenMP parallelization through Carpet/LoopControl in addition to MPI parallelization through Carpet
- multi-block code infrastructures by applying the Jacobian to transform local derivatives to global derivatives
Relativistic Magnetohydrodynamics
GRHydro
The Einstein Toolkit GRHydro modules can evolve spacetimes with general relativistic hydrodynamics in 3D Cartesian coordinates. GRHydro was once based on the public
version of the Whisky code developed originally by the EU Network on Sources of Gravitational Radiation and later by a collaboration
led by AEI/SISSA, but was later expanded and cleaned up considerably. Features of GRHydro include at the moment:
- Evolution of the equations of general relativistic magneto-hydrodynamics (GRMHD) in 3D Cartesian coordinates on a curved dynamical background.
IllinoisGRMHD
IllinoisGRMHD solves the equations of General Relativistic MagnetoHydroDynamics (GRMHD) using a high-resolution shock capturing scheme. It is a rewrite of the Illinois
Numerical Relativity (ILNR) group's GRMHD code, and generates results that agree to roundoff error with that original code. Its feature set coincides with the features of the
ILNR group's recent code (ca. 2009--2014), which was used in their modeling of the following systems:
- Magnetized circumbinary disk accretion onto binary black holes
- Magnetized black hole--neutron star mergers
- Magnetized Bondi flow, Bondi-Hoyle-Littleton accretion
- White dwarf--neutron star mergers
IllinoisGRMHD is particularly good at modeling GRMHD flows into black holes without the need for excision. Its HARM-based conservative-to-primitive solver has also been
modified to check the physicality of conservative variables prior to primitive inversion, and move them into the physical range if they become unphysical.
Initial Data
- Single and binary black holes
- Single TOV stars
- LORENE data
Relativity Tools
- Apparent horizon finding
- Black hole excision
Analysis
- TrK, det(g), R_ab, R
- ADM constraint violation
- Basic hydrodynamics analysis routines
- Extraction of gravitational waves
Computational Infrastructure
- Adaptive mesh refinement
- Reflection and rotation symmetry boundary conditions
- Radiation boundary conditions
- Flexible Cartesian 3-D meshes
- Multidimensional I/O using HDF5, ASCII, Jpegs
- Method of lines time integration
- Courant time steeping
- Seamless use of BLAS, GSL, HDF5, LAPACK
Tools
- Checking for NaNs
- Memory poisoning to identify uninitialized variables
- Timing report by thorn, schedule bin, and method