Physics 77 final project

This is a set of codes for private project.

Team member: Yukei, Tom, Savannah

Updated: 11/21/2018

Physics 77 project team 2018. All rights reserved.

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what to do:

• N-body simulation of galaxy development(2D?)
• Animation of simulated data

how to do:

• Take initial condition of N-particles (coordinate and velocity)

• Run gravitational simulation to calculate next position and velocity

• Loop above

• After creating data table (coordinate axis and time axis), show animation

initial condition:

• almost uniform distribution of particles with small random fluctuation of density
• having tangential velocity against single center point (origin)

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System Overview

# starlist: 	Table of star information at given time. 
#		Contains (1) coordinate and (2) velocity 
#		for each particle (=star).
# gal_hist: 	History of the Galaxy. 
#		Table of starlist with time axis.

note: function names are represented by bold letters

1. data_read():

   • Take in initial 'starlist'

2. Prepare an array as gal_hist

3. time_development(): for time t_next,

   1. Prepare 'starlist_next'
   2. Starloop(): for star[i],
      1. net_force():
         • calculate force between i-j
           • dist(): calculate distance
           • force_ij(): calculate force value
         • components(): break force in component form
         • add all force in component form
         • get (return) net force on star[i]
      2. accel():
         • get (return) acceleration of star[i]
      3. pos():
         • get (return) next coordinate from r & v & a
      4. vel():
         • get (return) next velocity from v & a
      5. append star[i]'s data to 'starlist_next'
   3. vStack 'starlist_next' to 'gal_hist'

4. animate():

   • show animation of position of stars over time