def brownTest():
"""Testing for brownian motion plot"""
global mySys, fig, ax
reload(objects)
reload(system)
reload(core)
Writer = animation.writers['ffmpeg']
writer = Writer(fps=core.FRAMERATE, bitrate=1800)
balls = objects.distributeBalls(60, 5, ballsize=0.1, v=20.)
big_ball = objects.BigBall(pos=[7, 0, 0], radius=1., mass=5)
balls.append(big_ball)
cont = objects.Container(9)
mySys = system.System(balls, cont)
fig = plt.figure()
ax = plt.axes(xlim=(-20, 20), ylim=(-20, 20))
ax.axes.set_aspect('equal')
mySys.init_system(ax)
anim = animation.FuncAnimation(fig,
mySys.next_frame,
frames=200,
interval=20,
blit=True,
repeat=False)
anim.save("mov.mp4", writer=writer)
fig2 = plt.figure(2)
ax2 = plt.axes(xlim=(-20, 20), ylim=(-20, 20))
ax2.add_artist(plt.Circle((0, 0), 9, fill=False))
nodes = big_ball.get_nodes()
plt.plot(nodes[0], nodes[1])
plt.savefig("brown.png")
def conservationTest(step=5):
"""Run the system for *step* seconds to check physics works"""
global mySys
sys.setrecursionlimit(10000)
reload(objects)
reload(system)
reload(core)
balls = objects.distributeBalls(20, 12, ballsize=0.1)
cont = objects.Container(12)
mySys = system.System(balls, cont)
mySys.init_system(None)
E0 = mySys.total_KE()
p0 = mySys.get_total_momentum()
mySys.check_collide(step)
E1 = mySys.total_KE()
p1 = mySys.get_total_momentum()
if core.close(p0, p1):
core.logging.log(20, "Momentum conserved")
else:
core.logging.log(50, "Momentum not conserved")
core.logging.log(50, p0)
core.logging.log(50, p1)
if np.abs(E0 - E1) < 1E-30:
core.logging.log(20, "Energy conserved")
else:
core.logging.log(50, "Energy not conserved")
core.logging.log(50, E0)
core.logging.log(50, E1)
def genMaxwellBData(v=15.):
# params
rad = 12.
ballsize = 0.2
num_balls = 400
# INITIALIZE SYSTEM
balls = objects.distributeBalls(num_balls, rad, ballsize, v, 3)
cont = objects.Container(rad)
mySys = system.System(balls, cont)
mySys.init_system(None)
vels = []
for ball in balls:
v = ball.get_vel()
vels.append(np.dot(v, v))
v_bar = np.mean(vels)
# 5 times charictersitic collision time
t = 5. * ((4. / 3.) * np.pi * rad**3) / (
np.sqrt(v_bar) * 4. * np.pi * ballsize**2 * num_balls)
mySys.advance(t)
vels = []
for ball in balls:
v = ball.get_vel()
vels.append(np.sqrt(np.dot(v, v)))
temp = mySys.temperature()
return vels, temp
def genTest(n=6):
"""To be used interactively. Generate system of *n* balls as mySys"""
global mySys
reload(objects)
reload(system)
reload(core)
balls = objects.distributeBalls(n, 12)
cont = objects.Container(12.)
mySys = system.System(balls, cont)
def pressure(num_balls, ballsize, v, dim):
balls = objects.distributeBalls(
n=num_balls, radius=12, ballsize=ballsize, v=v, dim=dim)
cont = objects.Container(12)
mySys = system.System(balls, cont)
mySys.init_system(None)
mySys.check_collide(2)
P = mySys.pressure(5)
T = mySys.temperature()
return [P, T]
def pressure(num_balls, ballsize, v, dim):
balls = objects.distributeBalls(n=int(np.ceil(num_balls)),
radius=12,
ballsize=ballsize,
v=v,
dim=dim)
for ball in balls[int(np.ceil(num_balls / 2.)):]:
# Bad and wrong, but I don't want to write another method just
# for a test.
ball._radius = ballsize / 2.
cont = objects.Container(12)
mySys = system.System(balls, cont)
mySys.init_system(None)
mySys.check_collide(2)
P = mySys.pressure(5)
T = mySys.temperature()
return [P, T]
def animGenTest(n=6, r=12., ballsize=1.):
"""
Create animation with *n* balls, size *ballsize* in container radius *r*
"""
global mySys, fig, ax
reload(objects)
reload(system)
reload(core)
balls = objects.distributeBalls(n, r, ballsize=ballsize)
cont = objects.Container(r)
mySys = system.System(balls, cont)
fig = plt.figure()
ax = plt.axes(xlim=(-20, 20), ylim=(-20, 20))
ax.axes.set_aspect('equal')
mySys.init_system(ax)
anim = animation.FuncAnimation(fig,
mySys.next_frame,
interval=20,
blit=True)
plt.show()
def physicsTest(num_balls=200, ballsize=0.01):
global mySys, pressure
sys.setrecursionlimit(10000)
reload(objects)
reload(system)
reload(core)
balls = objects.distributeBalls(n=num_balls, radius=12, ballsize=ballsize)
cont = objects.Container(12)
mySys = system.System(balls, cont)
mySys.init_system(None)
mySys.check_collide(5)
P = mySys.pressure(20)
print "pressure", P
print "temp", mySys.temperature()
core.logging.log(50, "temp is {}".format(mySys.temperature()))
a = P * (4. / 3.) * np.pi * 12.**3
b = num_balls * core.Kb * mySys.temperature()
c = P * (((4. / 3.) * np.pi * 12.**3) -
((16. / 3.) * np.pi * ballsize**3 * num_balls))
print "Pv", a
print "nkT", b
print "frac", a / b
print "P(V-bn)", c
print "frac", c / b
