Particles - hyschive/gamer-fork GitHub Wiki

Compilation Options

Related options: PARTICLE ,   FLOAT8_PAR ,   STORE_PAR_ACC ,   STAR_FORMATION ,   PAR_NATT_USER  

Runtime Parameters

Parameters described on this page: PAR_INIT,   PAR_NPAR,   PAR_IC_FORMAT,   PAR_IC_FLOAT8,   PAR_IC_MASS,   PAR_IC_TYPE,   PAR_INTERP,   PAR_INTEG,   PAR_TR_INTERP,   PAR_TR_INTEG,   PAR_IMPROVE_ACC,   PAR_PREDICT_POS,   PAR_REMOVE_CELL,   OPT__FREEZE_PAR  

Other related parameters: DT__PARVEL ,   DT__PARVEL_MAX ,   DT__PARACC ,   OPT__FLAG_NPAR_PATCH ,   OPT__FLAG_NPAR_CELL ,   OPT__FLAG_PAR_MASS_CELL ,   OPT__PARTICLE_COUNT ,   LB_INPUT__PAR_WEIGHT ,   OPT__CK_PARTICLE  

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

• PAR_INIT   (1=function, 2=restart, 3=PAR_IC file)   [none]

  • Description: Initialization methods for particles. PAR_INIT=1: using a particle initialization function; see Setting IC from Analytical Functions — Particles . PAR_INIT=2: restarting from a simulation snapshot . PAR_INIT=3: loading a binary file named PAR_IC; see Setting IC from Files — Particles .
  • Restriction: It will be automatically reset to PAR_INIT=2 when adopting OPT__INIT =2.

• PAR_NPAR   (≥0)   [none]

  • Description: Total number of particles.
  • Restriction: Must be set when PAR_INIT=1/3; must be consistent with the number of particles loaded from an initial condition file (e.g., for PAR_INIT=3 and test problems with their own particle initializers); useless when restarting from a snapshot (i.e., PAR_INIT=2); must be an integer.

• PAR_IC_FORMAT   (1=[attribute][id], 2=[id][attribute]; row-major)   [1]

  • Description: Data format of the particle initial condition file PAR_IC used by PAR_INIT=3. See Setting IC from Files — Particles for details.
  • Restriction:

• PAR_IC_FLOAT8   (<0: same as FLOAT8_PAR , 0=single precision, 1=double precision)   [-1]

  • Description: Floating-point precision of the particle initial condition file PAR_IC.
  • Restriction:

• PAR_IC_MASS   (≥0.0; <0.0 → off)   [-1.0]

  • Description: Assigning this particle mass to all particles when adopting PAR_INIT=3. Note that when enabling this functionality (by setting PAR_IC_MASS≥0.0), the particle initial condition file PAR_IC should not include the particle mass data. See also Setting IC from Files — Particles .
  • Restriction:

• PAR_IC_TYPE   (≥0; <0 → off)   [-1]

  • Description: Assigning this particle type to all particles when adopting PAR_INIT=3. Note that when enabling this functionality (by setting PAR_IC_TYPE≥0), the particle initial condition file PAR_IC should not include the particle type data. See also Setting IC from Files — Particles .
  • Restriction:

• PAR_INTERP   (1=NGP, 2=CIC, 3=TSC)   [2]

  • Description: Massive particle interpolation schemes: NGP=nearest-grid-point, CIC=cloud-in-cell, TSC=triangular-shape cloud. Accuracy: TSC > CIC > NGP. Performance: NGP > CIC > TSC. In general, NGP is not recommended.
  • Restriction:

• PAR_INTEG   (1=Euler, 2=KDK)   [2]

  • Description: Massive particle integration scheme. Euler integration is only first-order accurate and is generally not recommended.
  • Restriction:

• PAR_TR_INTERP   (1=NGP, 2=CIC, 3=TSC)   [3]

  • Description: Tracer particle interpolation schemes. See PAR_INTERP for details.
  • Restriction:

• PAR_TR_INTEG   (1=Euler, 2=RK2)   [2]

  • Description: Tracer particle integration scheme. Euler integration is only first-order accurate and is generally not recommended.
  • Restriction:

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

  • Description: Improve the force accuracy for particles close to the patch boundaries.
  • Restriction: Only applicable when adopting PAR_INTERP=2/3 and enabling the compilation option STORE_POT_GHOST .

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

  • Description: Predict particle position during mass assignment to synchronize particles and grids.
  • Restriction:

• PAR_REMOVE_CELL   (≥0.0; <0.0 → set to default)   [depend]

  • Description: Remove particles too close to the simulation boundaries when adopting non-periodic boundary conditions. It is necessary because the force accuracy around the simulation boundaries may be deteriorated due to the potential extrapolation. Specifically, we remove particles located in the outermost PAR_REMOVE_CELL root cells in the simulation box. The default value is 1.0 ~ 2.0 depending on the adopted particle interpolation scheme (PAR_INTERP).
  • Restriction: Only applicable when adopting the isolated gravity boundary condition (i.e., OPT__BC_POT =2).

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

  • Description: Do not update particle position and velocity (except for tracer particles). It can be useful for evolving fluid in a static gravitational potential of particles.
  • Restriction:

Remarks

Links

• Main page of Runtime Parameters