An event based N-body-in-a-box simulator for ASTRO507 class at University of Washington 2018. See the Jupyter Notebook for full details.
These instructions will get you a copy of the project up and running on your local machine.
Developed and executed using the following packages
python-3.6.2
numpy-1.13.1
matplotlib-2.0.2
but it will most likely run on other versions too.
Clone this github repository and enter the target directory. Execute
$:> python
on the command prompt and import the package in the interpreter
>>> import nbody
It should work straight out of the box, if not - report a bug.
To get a quick simulation working try
import nbody
s = nbody.TDMSystem(N_particles=10, t_total=1)
s.simulate()
which should simulate a 1 second system of 10 particles in a box. Output should be a series of files called snapshot_t.ttt which are just text files containing the simulation state at the time of the snapshot. Different intial conditions are availible as well.
s = TDMSystem(10, 1, pos_type="ordered", vel_type="identical")
s = TDMSystem(10, 1, pos_type="random", vel_type="ekin_constrained", p_kin=1, p_r=0.02)
s = TDMSystem(10, 1, pos_type="ordered", vel_type="identical", p_v=1, p_mass=2)
Reading the docstrings should be fairly self-explanatory. The initial state generation functions are availible from the nbody module. Additional keyword arguments are passed to the initial state generation function so specifying them at TDMSystem instatiation is possible as well.
s = TDMSystem(10, 1, pos_type="ordered", edgespacing=0.1, pspacing=0.2, verbose=False)
See the doc-strings and the notebook for more details. It is possible to define your own generation function and use it instead of the ones provided by nbody. It is also possible to collide particles on an individual basis
p = nbody.Particle(pos=(0, 0), vel=(1, 0), mass=1, r=1)
t = nbody.Particle(pos=(3, 0), vel=(-1, 0), mass=1, r=1)
dt = p.dt2Hit(t)
p.move(dt)
p.collide2particle(t)
The simulation basically runs in the same way except additionally it keeps track of which collision should happend first by using a priority queue. See the notebook for more details on how exactly this is done.
The file thermo_sim_examples.tar.bz2 should contain all the examples required to succesfully execute the notebook once untared. Functionality to read the snaphsots or sets of snapshots by snapshot_data and sim_data functions. Otherwise the following should work as well.
import nbody
import matplotlib.pyplot as plt
# create a test system and a test snapshot
s = nbody.TDMSystem(10, 1)
s.snapshot(0)
# read the snapshot data in
snapshot = nbody.snapshot_data("snapshot_0.0")
# use one of the plotting utilities provided by nbody
fig, ax = plt.subplots()
nbody.plot_positions(ax, snapshot["x"], snapshot["y"])
plt.show()