This HTML automatically generated with rman for NEMO
Table of Contents
mktt72 - Create a Toomre & Toomre 1972 test disk
mktt72 [parameter=value]
mktt72 creates a test disk of particles similar to the one
used in Toomre & Toomre’s 1972 paper (1972ApJ...178..623T). Currently each ring
is placed in a separate snapshot. Use snapmerge(1NEMO)
if they must be in
a single snapshot. See EXAMPLES below.
The disk is rotating counter clock
wise. Use snapscale(1NEMO)
to flip the sign of velocities.
Another historic
program is the Holmberg 1941 light bulb experiment, see mkh41(1NEMO)
.
The following parameters are recognized in order; they may be given in
any order if the keyword is also given. Use --help to confirm this man page
is up to date.
- out=
- output file name, each ring in a separate snapshot(5NEMO)
.
Use snapmerge(1NEMO)
- nbody=
- number of particles per (first) ring. When
grow=t the number of particles increases to keep the line density constant.
[100]
- radius=
- radii of rings. They should be entered in increasing order
to prevent interesting effects when grow=t. [1:6:1]
- mass=
- Mass of the
central particle. This is used to compute the forces. Default: 1.0
- eps=
- Standard
softening length applied between central mass and test particles to compute
the forces that set the particles. Default: 0.0
- central=t|f
- Add the central
mass point also, as first snapshot? Default: f
- grow=t|f
- Grow the number
of particles per ring to keep the line density constant? Default: t
- headline=
- verbiage for output []
Create a single snapshot with 10 rings
and 16 in the first ring (and scaled to about 160 in the outer ring).
% mktt72 - 16 0.1:1:0.1 | snapmerge - snap.out
Here is a test to see if the force computations are ok, and rings stay
at the same radius. A large value of eps= is used to make sure the first
few rings are not pure 1/r^2:
% mktt72 - 10 radius=0.1:1:0.1 central=t eps=0.2 |\
snapmerge - - | hackcode1 - snap.out tstop=5 freq=100 freqout=10 eps=0.2
% snapxyz snap.out - | xyzview -
It is near impossible to create the exact same initial conditions
(at T=-10) of the TT72 paper. A few quotes from the paper:
In each example,
one of the two point masses arrives at the scene of the encounter surrounded
by a flat, annular disk of 120 test particles; the other arrives bare. More
exactly, the unperturbed disk consists of five discrete rings, of 12,18,
24, 30, and 36 particles apiece.
Test-particle results in this paper stem
from fourth-order Runge-Kutta numerical integrations of the restricted three-body
equations of motion
mkconfig(1NEMO)
, mkh41(1NEMO)
, mkdisk(1NEMO)
,
snapscale(1NEMO)
, snapstack(1NEMO)
2010ApJ...725..353D - D’Onghia et al. (2010)
- Quasi-resonant Theory of Tidal Interactions
@ads 1972ApJ...178..623T
Peter
Teuben
19-Nov-02 V0.1 Created PJT
5-dec-02 V0.3 added grow=,central= PJT
Table of Contents