Table of Contents
mkdisk - create a uniform-density test disk in an external potential
mkdisk out=snapshot [parameters=values ...]
mkdisk sets
up a uniform ``cold'' disk of test particles orbiting counter clockwise (but
see sign= below) in the gravitational potential of a user-supplied potential
(in potential(5NEMO)
format).
An input (snapshot) dataset can be given,
in which case the positions are taken from this input file.
The
following parameters are recognized in any order if the keyword is also
given:
- out=out_file
- The data are written to this file in snapshot(5NEMO)
format [no default].
- nbody=num_bodies
- Number of bodies particles [default:
2048]
- potname=potential_name
- name of the potential, see $NEMOOBJ/potential
for the current object repository. The user can supply his own, see potential(5NEMO)
.
[no default].
- potpars=pot_pars
- Paramaters to the user supplied potential.
The number of parameters depends on the potential supplied, the first parameter
is reserved for the pattern speed. [default: not supplied, parameters as
defined by potential(5)
].
- potfile=pot_data
- Optional data file(s) to the
user supplied potential. The number of files depends on the potential supplied.
[default: not supplied, or datafile(s) defined by potential(5)
].
- rmin=min_disk_radius
- Inner cutoff radius of test-particle disk. [Default: 0].
- rmax=max_disk_radius
- Outer cutoff radius of test-particle disk. [Default: 1].
- mass=tot_mass
- Total
mass of the disk. The default total mass is 0, since this is a testdisk.
Since there are a few programs that will not like mass-less particles, this
keyword can be used, or snapmass will have to be used before further action
is taken. [default: 0].
- frac=fraction
- The fraction that the local velocity
dispersion has w.r.t. the local rotation velocity. If a number is given, radial
and tangential velocity are by default taken to be the same, with no Z-velocities.
If two numbers are given, the first one is the radial dispersion, the second
one the tangential (currently wihtout any 2*Omega/Kappa correction), and
the Z dispersion 0. Finally, when 3 numbers are given, random motions in
Z are also added. [Default: 0]
- seed=random_seed
- Use random number seed. If
0 is given, a random number is generated from the time of the day. [default:
0].
- sign=-1|1
- Sign of the angular momentum. 1 means counter clockwise rotation
in the XY-plane (in case you were wondering, our galaxy has sign=-1). [Default:
1].
- in=infile
- Input file, in snapshot(5NEMO)
format, of which the positions
are used as initial conditions. [Default: not used]. *** lost the implementation
**
- angle=t|f
- Normally the particles are distributed randomly in phase,
but setting this to true, they will be regularly spread between 0 and TWO_PI.
Default: f
- vrad=
- A constant radial velocity (>0 means outward motion) added
to all particles. Default: 0.
- energy=t|f
- If random motions are added (see
frac=), the energy of each particle will change. By setting energy=t the
energy is conserved and the "circular" speed will be reduced. This way the
guiding center for epicyclic orbits will also be conserved. Note that this
only applies to motion in XY. For stars with too much random motion (if
frac too high), the random number generator is run again to ensure conserving
the planar motion kinetic energy. Default: false.
- headline=message
- Text headline
for output file [default: not used].
mktestdisk(1NEMO)
, mktt72(1NEMO)
,
mkbaredisk(1NEMO)
, snapcenter(1NEMO)
xx-feb-87 coding, still debugging PJT
21-Apr-87 V1.0: coding seems OK PJT
28-Apr-87 V1.1: keyword manss= added PJT
8-feb-89 V2.0: new implementation using potential(5) PJT
12-may-90 V3.0: new keywords for potential(5) PJT
12-mar-91 V4.0: NEMO 2.x PJT
9-jul-91 corrected a few lies in the documentation PJT
22-oct-91 V4.1: added in= optional input file PJT
12-jun-92 V4.2: nbody= is now second parameter, lost in= PJT
5-may-03 V4.4: added random Z motions by using frac= PJT
8-may-03 V4.5: added energy= PJT
Table of Contents