N-body Simulation

This is a code repository for a basic N-body simulation.

It is written in Python and utilizes the Leapfrog integration method to simulate the motion of particles in 3D space.

Requirements

• Python 3.6+
• Matplotlib
• Numpy
• Numba
• Json

Function Description

Run_sim(N_steps, pos_arr, mom_arr, mass_arr, start=0, dt=1.e-2, G=6.67408e-11, epsilon=0.01)

Output

This function runs the simulation and returns the following:

• pos_arr: An array containing the positions of the particles after the simulation.
• mom_arr: An array containing the momenta of the particles after the simulation.
• pos_data: An array containing the positions of the particles at each step of the simulation.

Input Parameters

N_steps : int
    The number of steps in the simulation.
pos_arr : numpy array
    An array containing the initial positions of the particles.
mom_arr : numpy array
    An array containing the initial momenta of the particles.
mass_arr : numpy array
    An array containing the masses of the particles.
start : int, optional
    The starting step of the simulation. Default is 0.
dt : float, optional
    The time step of the simulation. Default is 1.e-2.
G : float, optional
    The gravitational constant. Default is 6.67408e-11.
epsilon : float, optional
    The softening parameter. Default is 0.01.

Usage

• Execute the imports cell.
• Execute the Run_sim function definition in brute_force.ipynb .
• Provide the necessary inputs: N_steps, pos_arr, mom_arr, and mass_arr.
• Optional parameters such as start, dt, G, and epsilon can be modified to suit the needs of the simulation.
• Call the function Run_sim(N_steps, pos_arr, mom_arr, mass_arr, start=0, dt=1.e-2, G=6.67408e-11, epsilon=0.01) by assigning to a varialbe.
• Unpack the variable to get the pos_arr, mom_arr, pos_data.

Simulation video

• I have ran the simulation with 20000 parrticles in the mass range between 0.3 to 2.23 Solar Mass for a time period of 300 Myrs.
• The data from the runs were collected and animated into a video.
• The video runs at a rate of 1 Myr per sec.
• The video can befound here