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parameter_example.yml 18.12 KiB
# Define the system of units to use internally.
InternalUnitSystem:
  UnitMass_in_cgs:     1   # Grams
  UnitLength_in_cgs:   1   # Centimeters
  UnitVelocity_in_cgs: 1   # Centimeters per second
  UnitCurrent_in_cgs:  1   # Amperes
  UnitTemp_in_cgs:     1   # Kelvin

# Values of some physical constants
PhysicalConstants:
  G:            6.67408e-8 # (Optional) Overwrite the value of Newton's constant used internally by the code.

# Cosmological parameters
Cosmology:
  h:              0.6777        # Reduced Hubble constant
  a_begin:        0.0078125     # Initial scale-factor of the simulation
  a_end:          1.0           # Final scale factor of the simulation
  Omega_m:        0.307         # Matter density parameter
  Omega_lambda:   0.693         # Dark-energy density parameter
  Omega_b:        0.0455        # Baryon density parameter
  Omega_r:        0.            # (Optional) Radiation density parameter
  w_0:            -1.0          # (Optional) Dark-energy equation-of-state parameter at z=0.
  w_a:            0.            # (Optional) Dark-energy equation-of-state time evolution parameter.

# Parameters for the hydrodynamics scheme
SPH:
  resolution_eta:        1.2348   # Target smoothing length in units of the mean inter-particle separation (1.2348 == 48Ngbs with the cubic spline kernel).
  CFL_condition:         0.1      # Courant-Friedrich-Levy condition for time integration.
  h_tolerance:           1e-4     # (Optional) Relative accuracy of the Netwon-Raphson scheme for the smoothing lengths.
  h_max:                 10.      # (Optional) Maximal allowed smoothing length in internal units. Defaults to FLT_MAX if unspecified.
  max_volume_change:     1.4      # (Optional) Maximal allowed change of kernel volume over one time-step.
  max_ghost_iterations:  30       # (Optional) Maximal number of iterations allowed to converge towards the smoothing length.
  initial_temperature:   0        # (Optional) Initial temperature (in internal units) to set the gas particles at start-up. Value is ignored if set to 0.
  minimal_temperature:   0        # (Optional) Minimal temperature (in internal units) allowed for the gas particles. Value is ignored if set to 0.
  H_mass_fraction:       0.755    # (Optional) Hydrogen mass fraction used for initial conversion from temp to internal energy. Default value is derived from the physical constants.
  H_ionization_temperature: 1e4   # (Optional) Temperature of the transition from neutral to ionized Hydrogen for primoridal gas.

# Parameters for the self-gravity scheme
Gravity:
  mesh_side_length:       32        # Number of cells along each axis for the periodic gravity mesh.
  eta:          0.025               # Constant dimensionless multiplier for time integration.
  theta:        0.7                 # Opening angle (Multipole acceptance criterion).
  comoving_softening:     0.0026994 # Comoving softening length (in internal units).
  max_physical_softening: 0.0007    # Physical softening length (in internal units).
  rebuild_frequency:      0.01      # (Optional) Frequency of the gravity-tree rebuild in units of the number of g-particles (this is the default value).
  a_smooth:     1.25                # (Optional) Smoothing scale in top-level cell sizes to smooth the long-range forces over (this is the default value).
  r_cut_max:    4.5                 # (Optional) Cut-off in number of top-level cells beyond which no FMM forces are computed (this is the default value).
  r_cut_min:    0.1                 # (Optional) Cut-off in number of top-level cells below which no truncation of FMM forces are performed (this is the default value).

# Parameters for the task scheduling
Scheduler:
  nr_queues:                 0         # (Optional) The number of task queues to use. Use 0  to let the system decide.
  cell_max_size:             8000000   # (Optional) Maximal number of interactions per task if we force the split (this is the default value).
  cell_sub_size_pair_hydro:  256000000 # (Optional) Maximal number of interactions per sub-pair hydro task  (this is the default value).
  cell_sub_size_self_hydro:  32000     # (Optional) Maximal number of interactions per sub-self hydro task  (this is the default value).
  cell_sub_size_pair_grav:   256000000 # (Optional) Maximal number of interactions per sub-pair gravity task  (this is the default value).
  cell_sub_size_self_grav:   32000     # (Optional) Maximal number of interactions per sub-self gravity task  (this is the default value).
  cell_sub_size_pair_stars:   256000000 # (Optional) Maximal number of interactions per sub-pair stars task  (this is the default value).
  cell_sub_size_self_stars:   32000     # (Optional) Maximal number of interactions per sub-self stars task  (this is the default value).
  cell_split_size:           400       # (Optional) Maximal number of particles per cell (this is the default value).
  cell_subdepth_grav:        2         # (Optional) Maximal depth the gravity tasks can be pushed down (this is the default value).
  max_top_level_cells:       12        # (Optional) Maximal number of top-level cells in any dimension. The number of top-level cells will be the cube of this (this is the default value).
  tasks_per_cell:            0         # (Optional) The average number of tasks per cell. If not large enough the simulation will fail (means guess...).
  mpi_message_limit:         4096      # (Optional) Maximum MPI task message size to send non-buffered, KB.

# Parameters governing the time integration (Set dt_min and dt_max to the same value for a fixed time-step run.)
TimeIntegration:
  time_begin:        0.    # The starting time of the simulation (in internal units).
  time_end:          1.    # The end time of the simulation (in internal units).
  dt_min:            1e-6  # The minimal time-step size of the simulation (in internal units).