GS2 has a lot of possible options for the initial condition. Of these, only a few are usually used: these are the typical and restarting
These options are the most useful for ordinary GS2 simulations:
"default"
: Gaussian in . See ginit_default. Input
parameters:
"default_odd"
: Guassian in multiplied by . See ginit_default_odd. Input parameters:
"noise"
: Noise along field line: each mode is given a random amplitude
between zero and one. The recommended choice for nonlinear runs. See
ginit_noise. Input parameters:
"single_parallel_mode"
: Initialise only with a single parallel mode
specified by either ikpar_init for periodic
boundary conditions or kpar_init for linked boundary
conditions. Only makes sense for linear calculations. See
ginit_single_parallel_mode
There are many more initialisation options for GS2, although the majority are unmaintained and are specific to the studies they were originally written for. Unfortunately, many are also undocumented, so it is difficult to say precisely what they do
"alf"
: Ion distribution function proportional to ; do not use."all_modes_equal"
: Initialise with every single parallel and
perpendicular mode given the same amplitude. Intended for linear
calculations"cgyro"
: CGYRO-like initialisation, constant amplitude for and zero amplitude for (see ginit_cgyro for
details)."cont"
: Restart, using current value of g
in memory; unsupported,
do not use."convect"
: Unsupported; do not use. Controlled by k0."gs"
: Randomly phased sines and cosines in density,
parallel velocity, and parallel and perpendicular
temperatures. Controlled by:
"harris"
: Controlled by k0. Unsupported; do not use.
"kpar"
: Initial perturbation in fields of form , except for parallel velocity
which uses is 90 degrees out of phase and uses . Density,
parallel velocity, and perpendicular and parallel temperatures can
all be controlled independently. Controlled by:
"kz0"
: Constant along a field line, that is initialise only with
.
"nl"
: Two modes set to constant amplitude. Controlled by:
"nl2"
: Two modes proportional to . Controlled by:
"nl3"
: Two modes with a Gaussian envelope, and
perturbation in fields of form , except for parallel velocity which uses is 90 degrees out
of phase and uses . Density, parallel velocity, and
perpendicular and parallel temperatures can all be controlled
independently. Controlled by:
ky
indices of modes: ikkkx
indices of modes: itt"nl3r"
: Similar to "nl3"
, but includes apar
.
"nl4"
: Unsupported and inconsistent over time; do not use."nl5"
: Unsupported; do not use."nl6"
: Unsupported; do not use."nl7"
: Unsupported; do not use."ot"
: Orszag-Tang 2D vortex problem (see aparamp,
phiamp, ittt, ikkk)"rh"
: Maxwellian perturbation in ik == 1
mode; do not use?"stationary_mode"
: Initialises the distribution function such that
it is a time-independent solution to the gyrokinetic equation when
collisions are neglected and only one mode (with aky = 0
) is
present. See Section 4 of the Analytic Geometry
Specification
documentation for more details."recon"
: Unsupported; do not use."recon3"
: Unsupported; do not use."test3"
: Unsupported; do not use."xi"
: Perturbation proportional to pitch angle, . Unlikely to
be useful."xi2"
: Perturbation proportional to . Unlikely to be
useful."zero"
: Sets distribution function to zeroThese options are used for restarting GS2. See Restarting a simulation for more details.
"restart"
, "many"
, or "file"
: Restart, using g
from restart files. See
ginit_restart_many."eig_restart"
: Uses the restart files written by the eigensolver. File to
read is set by restart_eig_id. See ginit_restart_eigIf GS2 has been built with parallel netCDF, then read_many
controls whether a single restart file or one file per processor is used.
You can scale the fields from the restart files with
scale. Note that if scale
is negative, the fields are scaled
by -scale / max(abs(phi))
!
These options are also used for restarting, but have additional behaviours. They are not well documented or maintained, so use at your own risk.
"no_zonal"
: Restart but remove the zonal flow component."small"
: Add restarted fields to a background as set by the "noise"
option."smallflat"
: Similar to "small"
, but with a different random background."zonal_only"
: Restart but set all non-zonal components of
the potential and the distribution function to 0. Input parameters: