Parameter File: par_ini.d

Main Simulation Parameters.

This file controls the core simulation setup, grid dimensions, evolution parameters, initial data settings, and output intervals.

The parameters must be listed in this specific order, as the code reads them sequentially using fscanf. Lines starting with # are ignored as comments.

1. mstep 

Maximum number of time steps for the simulation. The simulation will stop if this step count is reached, even if tmax is not.

Data Type:

Long Integer (long int)

Note

Read using ld. Corresponds roughly to mstep in main.

1. tmax 

Maximum physical time to evolve the simulation. The simulation will stop if the current time t exceeds tmax.

Data Type:

Double (double)

Note

Read using lf. Corresponds to Fmv0::tmax.

1. tab 

Number of buffer/ghost zones on each side of the physical domain boundary.

Data Type:

Integer (int)

Note

Read using d. Defines the thickness of the boundary region used for finite differencing stencils. Corresponds to Fmv0::tab.

1. amp 

Amplitude parameter for the inhomogeneous grid mapping function funcf. Controls the degree of grid stretching/compression. amp=0 corresponds to a uniform Cartesian grid.

Data Type:

Double (double)

Note

Read using lf. Used in Fmv0::funcf, Fmv0::df, Fmv0::ddf, Fmv0::dddf. Corresponds to Fmv0::amp.

1. nxmin 

Minimum grid index in the x-direction for the physical domain (excluding buffers).

Data Type:

Integer (int)

Note

Read using d. Often 0 for quadrant symmetry. Corresponds to jlower in the Fmv0 constructor.

1. nxmax 

Maximum grid index in the x-direction for the physical domain (excluding buffers).

Data Type:

Integer (int)

Note

Read using d. Corresponds to jupper in the Fmv0 constructor. The number of physical points in x is nxmax - nxmin + 1.

1. nymin 

Minimum grid index in the y-direction for the physical domain.

Data Type:

Integer (int)

Note

Read using d. Corresponds to klower in the Fmv0 constructor.

1. nymax 

Maximum grid index in the y-direction for the physical domain.

Data Type:

Integer (int)

Note

Read using d. Corresponds to kupper in the Fmv0 constructor.

1. nzmin 

Minimum grid index in the z-direction for the physical domain.

Data Type:

Integer (int)

Note

Read using d. Corresponds to llower in the Fmv0 constructor.

1. nzmax 

Maximum grid index in the z-direction for the physical domain.

Data Type:

Integer (int)

Note

Read using d. Corresponds to lupper in the Fmv0 constructor.

1. xmin 

Minimum coordinate value in the x-direction corresponding to nxmin.

Data Type:

Double (double)

Note

Read using lf. Corresponds to xlower in the Fmv0 constructor.

1. xmax 

Maximum coordinate value in the x-direction corresponding to nxmax.

Data Type:

Double (double)

Note

Read using lf. Corresponds to xupper in the Fmv0 constructor.

1. ymin 

Minimum coordinate value in the y-direction corresponding to nymin.

Data Type:

Double (double)

Note

Read using lf. Corresponds to ylower in the Fmv0 constructor.

1. ymax 

Maximum coordinate value in the y-direction corresponding to nymax.

Data Type:

Double (double)

Note

Read using lf. Corresponds to yupper in the Fmv0 constructor.

1. zmin 

Minimum coordinate value in the z-direction corresponding to nzmin.

Data Type:

Double (double)

Note

Read using lf. Corresponds to zlower in the Fmv0 constructor.

1. zmax 

Maximum coordinate value in the z-direction corresponding to nzmax.

Data Type:

Double (double)

Note

Read using lf. Corresponds to zupper in the Fmv0 constructor.

1. cfl 

Courant-Friedrichs-Lewy (CFL) factor. Used to determine the time step dt based on the grid spacing (dt = cfl * dx).

Data Type:

Double (double)

Note

Read using lf. Typical values are less than 0.5 for stability. Corresponds to Fmv0::cfl.

1. cdt 

Factor for cosmological time scale adjustment of dt. dt is set to min(cfl*dx, cdt*cfl/|trK|).

Data Type:

Double (double)

Note

Read using lf. Allows dt to adapt to the Hubble expansion rate. Corresponds to cdt in main.

1. etaa 

Gauge parameter eta for the 1+log lapse evolution condition. Controls the damping/driving of the lapse.

Data Type:

Double (double)

Note

Read using lf. Corresponds to Fmv0::etaa.

1. etab 

Gauge parameter eta for the Gamma-driver shift evolution condition. Controls the damping of the shift auxiliary variable B^i.

Data Type:

Double (double)

Note

Read using lf. Corresponds to Fmv0::etab.

1. etabb 

Gauge parameter eta_b (or similar) for the Gamma-driver shift evolution condition. Multiplies B^i in the evolution equation for beta^i.

Data Type:

Double (double)

Note

Read using lf. Corresponds to Fmv0::etabb.

1. KOep 

Coefficient epsilon for Kreiss-Oliger numerical dissipation. Controls the strength of artificial dissipation added to suppress high-frequency noise.

Data Type:

Double (double)

Note

Read using lf. Corresponds to Fmv0::KOep.

1. exg 

Grid size (radius in grid points) for the square excision region around the origin. Used if excision is enabled.

Data Type:

Integer (int)

Note

Read using d. Corresponds to Fmv0::exg.

1. contn 

Flag to indicate whether to continue from a previous simulation. 0 = start new simulation, 1 = continue from file.

Data Type:

Integer (int)

Note

Read using d. Corresponds to contn in main.

1. file_continue 

Name of the file to read data from if contn is set to 1.

Data Type:

String (char[])

Note

Read using s. Ensure the filename doesn't contain spaces. Corresponds to file_continue in main.

1. mu 

Amplitude parameter for the initial geometric perturbation (e.g., related to conformal factor Psi).

Data Type:

Double (double)

Note

Read using lf. Used in Fmv::initial_nonsph.

1. kk 

Scale or wave number parameter for the initial geometric perturbation.

Data Type:

Double (double)

Note

Read using lf. Used in Fmv::initial_nonsph.

1. xi2 

Non-spherical deformation parameter (likely quadrupole-like) for the initial geometric perturbation.

Data Type:

Double (double)

Note

Read using lf. Used in Fmv::initial_nonsph.

1. xi3 

Non-spherical deformation parameter for the initial geometric perturbation.

Data Type:

Double (double)

Note

Read using lf. Used in Fmv::initial_nonsph.

1. w3 

Additional non-spherical parameter, possibly related to time dependence or frequency, for the initial geometric perturbation.

Data Type:

Double (double)

Note

Read using lf. Used in Fmv::initial_nonsph.

1. mus 

Amplitude parameter for the initial scalar field perturbation.

Data Type:

Double (double)

Note

Read using lf. Used in Fmv::set_initial_scalar.

1. kks 

Scale or wave number parameter for the initial scalar field perturbation.

Data Type:

Double (double)

Note

Read using lf. Used in Fmv::set_initial_scalar.

1. xi2s 

Non-spherical deformation parameter for the initial scalar field perturbation.

Data Type:

Double (double)

Note

Read using lf. Used in Fmv::set_initial_scalar.

1. xi3s 

Non-spherical deformation parameter for the initial scalar field perturbation.

Data Type:

Double (double)

Note

Read using lf. Used in Fmv::set_initial_scalar.

1. Hb 

Initial Hubble parameter value. Used for setting up cosmological initial data.

Data Type:

Double (double)

Note

Read using lf. Corresponds to Fmv0::Hb.

1. fluidw 

Equation of state parameter w for the fluid (assuming P = w * rho or similar).

Data Type:

Double (double)

Note

Read using lf. Corresponds to Fmv0::fluidw. E.g., 0 for dust, 1/3 for radiation.

1. Mkap 

Parameter kappa for MUSCL (Monotonic Upstream-centered Scheme for Conservation Laws) reconstruction used in fluid evolution. Controls the order/type of interpolation.

Data Type:

Double (double)

Note

Read using lf. Corresponds to Fmv0::kap_MUSCL.

1. bminmod 

Parameter b for the minmod slope limiter function used in fluid evolution reconstruction. Controls the limiter's behavior.

Data Type:

Double (double)

Note

Read using lf. Corresponds to Fmv0::b_minmod.

1. ptintval1 

Time interval for printing output during the first phase of the simulation (before changept).

Data Type:

Double (double)

Note

Read using lf. Corresponds to ptintval1 in main.

1. ptintval2 

Time interval for printing output during the second phase of the simulation (after changept).

Data Type:

Double (double)

Note

Read using lf. Corresponds to ptintval2 in main.

1. changept 

Time at which the printing interval switches from ptintval1 to ptintval2.

Data Type:

Double (double)

Note

Read using lf. Corresponds to changept in main.