To include cosmological expansion in your FLASH executable, include the line
REQUESTS physics/Cosmology/in your setup's Config file. At present the Cosmology unit in FLASH4 is built around the MatterLambdaKernel. This kernel assumes the contribution of radiation to be negligible in comparison with those of matter and the cosmological constant.
The runtime parameters available with
the Cosmology unit are described in Table 22.1.
Note that the total effective mass density is not explicitly specified but
is inferred from the sum of the OmegaMatter, OmegaRadiation,
and CosmologicalConstant parameters. The MaxScaleChange parameter
sets the maximum allowed fractional change in the scale factor
during a single
timestep. This behavior is enforced by the Cosmology_computeDt routine. The
default value is set to the system's HUGE value for a double precision
real floating point value
to avoid interfering with non-cosmological simulations.
Parameter | Type | Default | Description |
useCosmology | BOOLEAN | .true. | True if cosmology is to be used in this simulation |
OmegaMatter | REAL | 0.3 | Ratio of total mass density to
critical density at the present
epoch (![]() |
OmegaBaryon | REAL | 0.05 | Ratio of baryonic (gas) mass
density to critical density at
the present epoch; must be
![]() ![]() |
CosmologicalConstant | REAL | 0.7 | Ratio of the mass density
equivalent in the cosmological
constant to the critical density
at the present epoch
(
![]() |
OmegaRadiation | REAL |
![]() |
Ratio of the mass density
equivalent in radiation to the
critical density at the present
epoch (![]() |
HubbleConstant | REAL |
![]() |
Value of the Hubble constant ![]() ![]() |
MaxScaleChange | REAL | HUGE(1.) | Maximum permitted fractional change in the scale factor during each timestep |