Input Deck Reference

Auto-generated from schema.lua. Each table below documents one section of the config table.

config.basis

Key	Type	Default	Required	Description
nnodes	double	—	No	Number of DG nodes per cell.

config.bc

radiation

Key	Type	Default	Required	Description
bc_i	string	—	No	Inner radiation boundary condition. Options: ‘reflecting’, ‘outflow’, ‘marshak’, ‘dirichlet’.
dirichlet_values_i	array	—	No	Dirichlet state values at inner boundary.
dirichlet_values_o	array	—	No	Dirichlet state values at outer boundary.
bc_o	string	—	No	Outer radiation boundary condition. Options: ‘reflecting’, ‘outflow’, ‘dirichlet’.

fluid

Key	Type	Default	Required	Description
bc_i	string	—	No	Inner fluid boundary condition. Options: ‘reflecting’, ‘outflow’, ‘dirichlet’, ‘periodic’.
dirichlet_values_i	array	—	No	Dirichlet state values at inner boundary.
dirichlet_values_o	array	—	No	Dirichlet state values at outer boundary.
bc_o	string	—	No	Outer fluid boundary condition. Options: ‘reflecting’, ‘outflow’, ‘dirichlet’, ‘periodic’.

config.composition

Key	Type	Default	Required	Description
ncomps	int	—	No	Number of composition species.

config.engine

thermal

Key	Type	Default	Required	Description
tend	double	—	No	End time for energy injection. Must be > 0.
mend	double	—	No	Mass coordinate of injection upper boundary in Msun. Must be > 0.
enabled	bool	—	No	Enable thermal energy injection engine.
energy	double	—	No	Total injected energy in erg.
mode	string	—	No	Injection mode. Options: ‘direct’, ‘asymptotic’.
operator_split	bool	false	No	Apply engine as operator-split source.

config.eos

Key	Type	Default	Required	Description
n	double	—	No	Polytropic index n. Required for polytropic EOS.
type	string	—	No	Equation of state type. Options:. ‘ideal’, ‘paczynski’, ‘marshak’, ‘polytropic’.
gamma	double	1.4	No	Adiabatic index. Default: 1.4.
k	double	—	No	Polytropic constant K. Required for polytropic EOS.

config.fluid

limiter

Key	Type	Default	Required	Description
type	string	minmod	No	Limiter type. Options: ‘minmod’, ‘moment’, ‘weno [experimental]’.
gamma_l	double	—	No	WENO left weight. Inferred from gamma_i if omitted.
b_tvd	double	1.0	No	TVD parameter b. Used with minmod limiter.
characteristic	bool	false	No	Enable characteristic limiting.
tci_opt	bool	false	No	Enable troubled-cell indicator.
enabled	bool	true	No	Enable slope limiter for fluid.
weno_r	double	2.0	No	WENO smoothness exponent. Must be > 0.
m_tvb	double	0.0	No	TVB parameter M. Used with minmod limiter.
gamma_r	double	—	No	WENO right weight. Inferred from gamma_i if omitted.
gamma_i	double	—	No	WENO central weight. Required for WENO limiter.
tci_val	double	—	No	Troubled-cell indicator threshold.

config.gravity

Key	Type	Default	Required	Description
operator_split	bool	false	No	Apply gravity as an operator-split source.
model	string	—	No	Gravity model. Options: ‘constant’, ‘spherical’.
gval	double	—	No	Gravitational acceleration (constant model). Must be > 0.

config.heating

nickel

Key	Type	Default	Required	Description
operator_split	bool	false	No	Apply nickel heating as operator-split source.
model	string	—	No	Nickel heating model. Options. ‘jeffery’ and ‘full_trapping’.
enabled	bool	—	No	Enable Ni56 decay heating.

config.ionization

Key	Type	Default	Required	Description
fn_degeneracy	string	—	No	Path to degeneracy factors atomic data file.
solver	string	linear	No	Saha solver mode. Options: ‘linear’, ‘log’.
fn_ionization	string	—	No	Path to ionization atomic data file.
ncomps	int	—	No	Number of species for Saha solver.

config.opacity

Key	Type	Default	Required	Description
type	string	—	No	Opacity model. Options: ‘tabular’, ‘constant’, ‘powerlaw’.
filename	string	—	No	Path to tabular opacity HDF5 file.
kR	double	—	No	Rosseland mean opacity (cm^2/g). Required for constant and powerlaw.
t_exp	double	—	No	Temperature exponent for powerlaw opacity.
rho_exp	double	—	No	Density exponent for powerlaw opacity.
kR_offset	double	0.0	No	Rosseland opacity additive offset. Powerlaw only.
kP_offset	double	0.0	No	Planck opacity additive offset. Powerlaw only.
kP	double	—	No	Planck mean opacity (cm^2/g). Required for constant and powerlaw.

floors

Key	Type	Default	Required	Description
core_planck	double	0.24	No	Core Planck floor. Used with core_envelope model.
type	string	core_envelope	No	Opacity floor model. Options: ‘core_envelope’, ‘constant’.
core_rosseland	double	0.24	No	Core Rosseland floor. Used with core_envelope model.
planck	double	0.001	No	Planck floor value. Used with constant floor model.
rosseland	double	0.001	No	Rosseland floor value. Used with constant floor model.
env_rosseland	double	0.01	No	Envelope Rosseland floor. Used with core_envelope model.
env_planck	double	0.01	No	Envelope Planck floor. Used with core_envelope model.

config.output

Key	Type	Default	Required	Description
dt_init	double	1.000000e-16	No	Initial timestep. Must be > 0.
ncycle_out	double	100	No	Number of cycles between stdout output.
dt_growth_frac	double	1.05	No	Initial timestep growth factor. Must be > 1.
dt_fixed	double	—	No	Fixed timestep override. Optional.
dt_hdf5	double	—	No	Time interval between HDF5 outputs. Default: t_end / 100.

history

Key	Type	Default	Required	Description
fn	string	athelas.hst	No	History output filename.
dt	double	—	No	Time interval between history writes. Default: dt_hdf5 / 10.

config.physics

Key	Type	Default	Required	Description
gravity	bool	false	No	Enable gravitational source terms.
composition	bool	false	No	Enable multi-species composition.
radiation	bool	false	No	Enable radiation transport.
heating	bool	false	No	Enable nuclear heating sources.
engine	bool	false	No	Enable energy injection engine.
ionization	bool	false	No	Enable Saha ionization. Requires composition = true.

config.problem

Key	Type	Default	Required	Description
t_end	double	—	No	End time of the simulation.
grid_type	string	—	No	Grid spacing type. Options: ‘uniform’, ‘logarithmic’.
xl	double	—	No	Left boundary of the domain.
nx	double	—	No	Number of grid cells. Must be > 0.
params	—	—	No	Problem-specific parameters. Validated by the problem generator.
nlim	double	-1	No	Maximum double of cycles. -1 for unlimited.
cfl	double	—	No	CFL double for timestep control. Must be > 0.
xr	double	—	No	Right boundary of the domain. Must be > xl.
geometry	string	—	No	Domain geometry. Options: ‘planar’, ‘spherical’.
name	string	—	No	Unique identifier for this simulation problem.

config.radiation

Key	Type	Default	Required	Description
discretization	string	—	No	Spatial discretization of the transport term. Options: ‘implicit’ or ‘explicit’.

limiter

Key	Type	Default	Required	Description
type	string	minmod	No	Limiter type. Options: ‘minmod’, ‘moment’, ‘weno [experimental]’.
gamma_l	double	—	No	WENO left weight. Inferred from gamma_i if omitted.
b_tvd	double	1.0	No	TVD parameter b. Used with minmod limiter.
characteristic	bool	false	No	Enable characteristic limiting. Currently unsupported for radiation.
tci_opt	bool	false	No	Enable troubled-cell indicator.
enabled	bool	true	No	Enable slope limiter for radiation.
weno_r	double	2.0	No	WENO smoothness exponent. Must be > 0.
m_tvb	double	0.0	No	TVB parameter M. Used with minmod limiter.
gamma_r	double	—	No	WENO right weight. Inferred from gamma_i if omitted.
gamma_i	double	—	No	WENO central weight. Required for WENO limiter.
tci_val	double	—	No	Troubled-cell indicator threshold.

timestep

Key	Type	Default	Required	Description
max_change_f	double	—	No	Maximum allowed absolute change in radiation reduced flux. Timestep control for implicit transport.
max_fractional_change_e	double	—	No	Maximum allowed fractional change in radiation energy. Timestep control for implicit transport.

newton

Key	Type	Default	Required	Description
max_iter	int	10	No	Maximum Newton iterations for implicit transport solve.
tol	double	1.000000e-08	No	Convergence tolerance for implicit transport Newton iteration.

config.time

Key	Type	Default	Required	Description
integrator	string	—	No	Time integration method. E.g. ‘IMEX_SSPRK11’, ‘IMEX_ARK32_ESDIRK’.