Runtime Parameters: Initial Conditions

Parameters described on this page: OPT__INIT,   OPT__INIT_BFIELD_BYVECPOT,   RESTART_LOAD_NRANK,   OPT__RESTART_RESET,   OPT__UM_IC_LEVEL,   OPT__UM_IC_NLEVEL,   OPT__UM_IC_NVAR,   OPT__UM_IC_FORMAT,   OPT__UM_IC_FLOAT8,   OPT__UM_IC_DOWNGRADE,   OPT__UM_IC_REFINE,   OPT__UM_IC_LOAD_NRANK,   OPT__INIT_RESTRICT,   INIT_SUBSAMPLING_NCELL,   OPT__FFTW_STARTUP  

Parameters below are shown in the format:   Name   (Valid Values)   [Default Value]

• OPT__INIT   (1=function, 2=restart, 3=UM_IC file)   [none]

  • Description: Grid initialization method. OPT__INIT=1: using analytical functions; see Setting IC from Analytical Functions — Grids. OPT__INIT=2: restarting from a simulation snapshot. OPT__INIT=3: loading a uniform-mesh binary file named UM_IC; see Setting IC from Files — Grids.
  • Restriction:

• OPT__INIT_BFIELD_BYVECPOT   (0=off, 1=file, 2=function)   [0]

  • Description: Set the magnetic field from either a vector potential file named B_IC (see Setting IC from Files — Magnetic Field) or an analytical vector potential function (see Setting IC from Functions — Magnetic Field).
  • Restriction: For --mhd only.

• RESTART_LOAD_NRANK   (>0)   [1]

  • Description: Number of parallel I/O for restart. In other words, RESTART_LOAD_NRANK MPI processes will load the restart file in parallel.
  • Restriction:

• OPT__RESTART_RESET   (0=off, 1=on)   [0]

  • Description: During restart, reset some of the simulation status parameters (e.g., step, time, snapshot ID) to their initial values as if the simulation starts over again.
  • Restriction:

• OPT__UM_IC_LEVEL   (0 ≤ input < --nlevel)   [0]

  • Description: Starting AMR level in the uniform-mesh initial condition file. See Setting IC from Files — Grids for details.
  • Restriction:

• OPT__UM_IC_NLEVEL   (1 ≤ input ≤ --nlevel-OPT__UM_IC_LEVEL)   [1]

  • Description: Number of AMR levels in the uniform-mesh initial condition file. See Setting IC from Files — Grids for details.
  • Restriction:

• OPT__UM_IC_NVAR   (0 ≤ input < total number of gas fields)   [total number of gas fields]

  • Description: Number of fluid variables stored in the uniform-mesh initial condition file. The default value is 5+--passive for --model=HYDRO. See Setting IC from Files — Grids for details.
  • Restriction:

• OPT__UM_IC_FORMAT   (1=[v][z][y][x], 2=[z][y][x][v]; row-major and v=field)   [1]

  • Description: Data format of the uniform-mesh initial condition file. See Setting IC from Files — Grids for details.
  • Restriction:

• OPT__UM_IC_FLOAT8   (<0: same as --double, 0=single precision, 1=double precision)   [-1]

  • Description: Floating-point precision of the uniform-mesh initial condition file.
  • Restriction:

• OPT__UM_IC_DOWNGRADE   (0=off, 1=on)   [1]

  • Description: Downgrade (i.e. derefine) the uniform-mesh initial condition data for cells not satisfying any refinement criteria. See Setting IC from Files — Grids for details.
  • Restriction:

• OPT__UM_IC_REFINE   (0=off, 1=on)   [1]

  • Description: Refine the uniform-mesh initial condition data from level OPT__UM_IC_LEVEL to MAX_LEVEL for cells satisfying the adopted refinement criteria. See Setting IC from Files — Grids for details.
  • Restriction:

• OPT__UM_IC_LOAD_NRANK   (>0)   [1]

  • Description: Number of parallel I/O for loading the uniform-mesh initial condition file. Specifically, it allows OPT__UM_IC_LOAD_NRANK MPI processes to load the initial condition file concurrently. But the actually achieved parallel I/O depends on the system specifications. See also Setting IC from Files — Grids.
  • Restriction:

• OPT__INIT_RESTRICT   (0=off, 1=on)   [1]

  • Description: For non-leaf patches, replace fluid data by the volume-weighted average of their child patch data. It is similar to the option OPT__FIXUP_RESTRICT except that it only applies to the initial condition.
  • Restriction:

• INIT_SUBSAMPLING_NCELL   (0=off, >0 → number of sub-cells along each direction)   [0]

  • Description: Perform sub-sampling when constructing the grid IC to make it smoother. Specifically, each cell will be divided into N_sub³ sub-cells when calling the grid IC function, where N_sub = INIT_SUBSAMPLING_NCELL, and then take the volume-weighted average of these sub-cells.
  • Restriction: Only applicable when adopting OPT__INIT=1.

• OPT__FFTW_STARTUP   (-1 → set to default, 0=ESTIMATE, 1=MEASURE, 2=PATIENT)   [-1]

  • Description: Initialize FFTW plans. MEASURE is recommended for the balance between FFTW plan initialization time and FFT performance. Note that simulation results can vary in each run on the level of machine precision for OPT__FFTW_STARTUP != ESTIMATE.
  • Restriction: PATIENT is not supported by FFTW2. Must use ESTIMATE when enabling --bitwise_reproducibility.

Remarks

Links

• Main page of Runtime Parameters
• Main page of Initial Conditions