nBody
A GPU-accelerated N-body particle simulator and animator
Create complex particle simulations the easy way: a high-level package for designing and simulating large-scale particle interactions. Let nBody do the hard work for you!
Features
Easy to use – and fast – nBody can simulate:
- Gravitational acceleration
- Coulomb interactions
- Particle collisions
nBody is highly optimized:
- GPU acceleration available via
cupy
- CPU multiprocessing with
numpy
- Energy conservation via the velocity-verlet algorithm
Animated matplotlib
visualizations included for 2-D simulations. 3-D animations are also supported through the use of vpython
.
Quick-Start
Using numpy
arrays, you will need:
- An initial position array
x
with shape(N,p)
- N is the number of particles
- p is the number of dimensions
- An initial velocity array
v
with shape(N,p)
- An array of masses
m
with shape(N,)
- An array of charges
q
with shape(N,)
- An array of radii
r
with shape(N,)
A possible configuration is as follows:
import numpy as np
x = np.random.normal(0, 10, (N,p)) # Positions
v = np.random.normal(0, 2, (N,p)) # Velocities
m = np.random.normal(8, 1, (N, )) # Masses
q = np.random.normal(0, 1E-6, (N, )) # Charges
r = np.random.normal(1, 0.1, (N, )) # Radii
m[m < 0] = np.abs(m[m < 0])
m[m == 0] = 1E-3
Next, pass these arrays in the given order to the spheres
function, so as to create a new instance S
of class System
with the above conditions.
from nbody import *
S = spheres(x, v, m, q, r)
After selecting a simulation runtime T
and (optional) time-step dt
, use the solve
method to calculate the particles' trajectories.
S.solve(T, dt)
If the system is 2-D such that p == 2
, an animation can be created and saved to file; here, the filename quick_start
is chosen, and will produce a file animations/quick_start.mp4
.
animate(S, "quick_start")
If the system is 3-D such that p == 3
, animations can be created but not saved to file – simply omit the string argument shown above, and no warnings will be raised.
Once the solve
method has been called, it is also possible to save the System
instance to file; in this case, the data will be saved to a directory saved/quick_start
.
save(S, "quick_start")