def bb79_cloud_evolve(N=50000,
Mcloud=1. | units.MSun,
Rcloud=3.2e16 | units.cm,
omega=1.56e-12 | units.rad / units.s,
density_perturb=0.5,
t_total=8.3e11 | units.s):
# mean density of the cloud
rho_uni = Mcloud / (4. / 3. * numpy.pi * Rcloud**3)
print(" ** mean density = ", rho_uni.in_(units.g / units.cm**3))
# free fall time of the cloud
t_ff = numpy.sqrt(3. * numpy.pi / (32. * units.constants.G * rho_uni))
print(" ** free-fall time = ", t_ff.in_(units.yr))
conv = nbody_system.nbody_to_si(Mcloud, Rcloud)
sph = Fi(conv)
# the initial conditions of BB79
parts_bb79 = bb79_cloud(targetN=N, omega=omega, rho_perturb=0.5,
ethep_ratio=0.25, convert_nbody=conv,
base_grid=body_centered_grid_unit_cube).result
sph.gas_particles.add_particles(parts_bb79)
sph.parameters.use_hydro_flag = True
sph.parameters.isothermal_flag = True
sph.parameters.integrate_entropy_flag = False
sph.parameters.gamma = 1
sph.parameters.verbosity = 0
sph.parameters.timestep = 0.1 * t_ff
print(
"**evolving to time: (end time = ~ {0:.3f} t_ff)".format(t_total / t_ff))
# setting snapshots to be plotted
nplot = 10
if nplot > 1:
plot_timestep = t_total / (nplot - 1)
else:
plot_timestep = t_total
# evolution of the cloud
for i in range(nplot):
ttarget = i * plot_timestep
t_tff = ttarget / t_ff
sph.evolve_model(ttarget)
plot_i = "bb79_rho_{0:03d}.png".format(i)
tt_tff = "{0:.3f}".format(t_tff)
title_i = "$%s\,t_{\mathrm{ff}}$" % (tt_tff)
print("\t {0:.3f} t_ff -> {1}".format(t_tff, plot_i))
plot_sph_rho(sph, N=300, grid_size=0.025 | units.parsec,
plot_name=plot_i, plot_title=title_i)
sph.stop()
def bb79_cloud_evolve(N=50000,
Mcloud=1. | units.MSun,
Rcloud=3.2e16 | units.cm,
omega=1.56e-12 | units.rad/units.s,
density_perturb=0.5,
t_total=8.3e11 | units.s):
# mean density of the cloud
rho_uni = Mcloud / (4./3.*numpy.pi*Rcloud**3)
print(" ** mean density = ", rho_uni.in_(units.g/units.cm**3))
# free fall time of the cloud
t_ff = numpy.sqrt(3.*numpy.pi / (32.*units.constants.G*rho_uni))
print(" ** free-fall time = ", t_ff.in_(units.yr))
conv = nbody_system.nbody_to_si(Mcloud, Rcloud)
sph = Fi(conv)
# the initial conditions of BB79
parts_bb79 = bb79_cloud(targetN=N, omega=omega, rho_perturb=0.5,
ethep_ratio=0.25, convert_nbody=conv,
base_grid=body_centered_grid_unit_cube).result
sph.gas_particles.add_particles(parts_bb79)
sph.parameters.use_hydro_flag = True
sph.parameters.isothermal_flag = True
sph.parameters.integrate_entropy_flag = False
sph.parameters.gamma = 1
sph.parameters.verbosity = 0
sph.parameters.timestep = 0.1*t_ff
print(
"**evolving to time: (end time = ~ {0:.3f} t_ff)".format(t_total/t_ff))
# setting snapshots to be plotted
nplot = 10
if nplot > 1:
plot_timestep = t_total / (nplot - 1)
else:
plot_timestep = t_total
# evolution of the cloud
for i in range(nplot):
ttarget = i*plot_timestep
t_tff = ttarget / t_ff
sph.evolve_model(ttarget)
plot_i = "bb79_rho_{0:03d}.png".format(i)
tt_tff = "{0:.3f}".format(t_tff)
title_i = "$%s\,t_{\mathrm{ff}}$" % (tt_tff)
print("\t {0:.3f} t_ff -> {1}".format(t_tff, plot_i))
plot_sph_rho(sph, N=300, grid_size=0.025 | units.parsec,
plot_name=plot_i, plot_title=title_i)
sph.stop()
def test1(self):
numpy.random.seed(1234)
mc = bb79_cloud(targetN=1000).result
self.assertEqual(len(mc), 1000)
ek = mc.kinetic_energy()
ep = mc.potential_energy(G=nbody_system.G)
eth = mc.thermal_energy()
self.assertAlmostEqual(eth / ep, -0.25, 2)
self.assertAlmostEqual(ek / ep, -0.2, 2)
def test1(self):
numpy.random.seed(1234)
mc=bb79_cloud(targetN=1000).result
self.assertEqual(len(mc),1000)
ek=mc.kinetic_energy()
ep=mc.potential_energy(G=nbody_system.G)
eth=mc.thermal_energy()
self.assertAlmostEqual(eth/ep, -0.25, 2)
self.assertAlmostEqual(ek/ep, -0.2, 2)
def test2(self):
numpy.random.seed(1234)
convert = nbody_system.nbody_to_si(1. | units.MSun, 3.2e16 | units.cm)
mc = bb79_cloud(targetN=1000, convert_nbody=convert).result
self.assertEqual(len(mc), 1000)
ek = mc.kinetic_energy()
ep = mc.potential_energy()
eth = mc.thermal_energy()
self.assertAlmostEqual(eth / ep, -0.25, 2)
self.assertAlmostEqual(ek / ep, -0.2, 2)
def test2(self):
numpy.random.seed(1234)
convert=nbody_system.nbody_to_si(1. | units.MSun,3.2e16| units.cm)
mc=bb79_cloud(targetN=1000,convert_nbody=convert).result
self.assertEqual(len(mc),1000)
ek=mc.kinetic_energy()
ep=mc.potential_energy()
eth=mc.thermal_energy()
self.assertAlmostEqual(eth/ep, -0.25, 2)
self.assertAlmostEqual(ek/ep, -0.2, 2)
