def head_on_stellar_merger(
masses = [0.3, 3.0] | units.MSun,
star_age = 310.0 | units.Myr,
maximally_evolved_stars = False,
initial_separation = 4.0 | units.RSun,
angle = numpy.pi / 3,
initial_speed = 3000.0 | units.km / units.s,
initial_speed_perpendicular = 30.0 | units.km / units.s,
number_of_sph_particles = 1000,
t_end = 1.0e4 | units.s,
sph_code = Fi,
steps_per_snapshot = 4,
snapshot_size = 100,
use_stored_stellar_models = True
):
"""
masses: Mass of the two stars
star_age: Initial age of the stars (if maximally_evolved_stars is False)
maximally_evolved_stars: Evolve stars as far as the Stellar Evolution code can get
number_of_sph_particles: Total number of particles of both stars, divided according to their masses
t_end: (Physical, not computational) duration of the hydrodynamics simulation
sph_code: Code to use for the hydrodynamics simulation
steps_per_snapshot: A hydroplot snapshot is generated each time after this many steps (0 or None means no snapshots)
snapshot_size: Size of the snapshot in pixels along one dimension
use_stored_stellar_models: Flag to use previously stored stellar model files (for speed-up).
"""
# Convert some of the input parameters to string, for use in output file names:
n_string = "n" + ("%1.0e"%(number_of_sph_particles)).replace("+0","").replace("+","")
t_end_string = "t" + ("%1.0e"%(t_end.value_in(units.s))).replace("+0","").replace("+","")
masses_string = ("m1_" + ("%0.3e"%(masses[0].value_in(units.MSun))).replace("+0","").replace("+","") +
"_m2_" + ("%0.3e"%(masses[1].value_in(units.MSun))).replace("+0","").replace("+",""))
if maximally_evolved_stars:
star_age_string = "a_max"
else:
star_age_string = "a" + ("%0.3e"%(star_age.value_in(units.Myr))).replace("+0","").replace("+","")
base_output_file_name = os.path.join(get_path_to_results(), "stellar_merger_"+n_string+"_"+t_end_string)
pickle_file_1 = os.path.join(get_path_to_results(), "stellar_merger_"+masses_string+"_"+star_age_string+"_1.pkl")
pickle_file_2 = os.path.join(get_path_to_results(), "stellar_merger_"+masses_string+"_"+star_age_string+"_2.pkl")
if not use_stored_stellar_models or not (os.path.exists(pickle_file_1) and os.path.exists(pickle_file_2)):
stars = Particles(2)
stars.mass = masses
try:
stellar_evolution = MESA()
stellar_evolution.initialize_code()
except:
print "MESA was not built. Returning."
return
stellar_evolution.commit_parameters()
stellar_evolution.particles.add_particles(stars)
stellar_evolution.commit_particles()
if maximally_evolved_stars:
try:
while True:
stellar_evolution.evolve_model()
except AmuseException as exception:
print exception
else:
stellar_evolution.evolve_model(star_age)
if os.path.exists(pickle_file_1):
print "Could not save stellar model 1: file already exists."
else:
pickle_stellar_model(stellar_evolution.particles[0], pickle_file_1)
print "Stellar model 1 saved at:", pickle_file_1
if os.path.exists(pickle_file_2):
print "Could not save stellar model 2: file already exists."
else:
pickle_stellar_model(stellar_evolution.particles[1], pickle_file_2)
print "Stellar model 2 saved at:", pickle_file_2
stellar_evolution.stop()
model_1 = StellarModel2SPH(None, None, pickle_file = pickle_file_1)
model_2 = StellarModel2SPH(None, None, pickle_file = pickle_file_2)
model_1.unpickle_stellar_structure()
model_2.unpickle_stellar_structure()
composition = model_2.composition_profile
midpoints = model_2.midpoints_profile[1:-1]
specific_internal_energy = model_2.specific_internal_energy_profile
number_of_sph_particles_1 = int(round(number_of_sph_particles *
(model_1.mass / (model_1.mass + model_2.mass))))
number_of_sph_particles_2 = number_of_sph_particles - number_of_sph_particles_1
print "Creating initial conditions from a MESA stellar evolution model:"
print model_1.mass, "star consisting of", number_of_sph_particles_1, "particles."
sph_particles_1 = convert_stellar_model_to_SPH(
None,
number_of_sph_particles_1,
seed=12345,
pickle_file = pickle_file_1
).gas_particles
print model_2.mass, "star consisting of", number_of_sph_particles_2, "particles."
sph_particles_2 = convert_stellar_model_to_SPH(
None,
number_of_sph_particles_2,
pickle_file = pickle_file_2
).gas_particles
initial_separation += model_1.radius + model_2.radius
sph_particles_2.x += numpy.cos(angle) * initial_separation
sph_particles_2.y += numpy.sin(angle) * initial_separation
sph_particles_1.vx += numpy.cos(angle) * initial_speed - numpy.sin(angle) * initial_speed_perpendicular
sph_particles_1.vy += numpy.cos(angle) * initial_speed_perpendicular + numpy.sin(angle) * initial_speed
view = [-0.5, 0.5, -0.5, 0.5] * (initial_separation + model_1.radius + model_2.radius)
all_sph_particles = ParticlesSuperset([sph_particles_1, sph_particles_2])
all_sph_particles.move_to_center()
unit_converter = ConvertBetweenGenericAndSiUnits(1.0 | units.RSun, constants.G, t_end)
hydro_legacy_code = sph_code(unit_converter)
n_steps = 100
hydro_legacy_code.parameters.n_smooth = 96
try:
hydro_legacy_code.parameters.timestep = t_end / n_steps
except Exception as exc:
if not "parameter is read-only" in str(exc): raise
hydro_legacy_code.gas_particles.add_particles(all_sph_particles)
times = [] | units.Myr
kinetic_energies = [] | units.J
potential_energies = [] | units.J
thermal_energies = [] | units.J
print "Evolving to:", t_end
for time, i_step in [(i*t_end/n_steps, i) for i in range(1, n_steps+1)]:
hydro_legacy_code.evolve_model(time)
times.append(time)
kinetic_energies.append( hydro_legacy_code.kinetic_energy)
potential_energies.append( hydro_legacy_code.potential_energy)
thermal_energies.append( hydro_legacy_code.thermal_energy)
if steps_per_snapshot and (not i_step % steps_per_snapshot):
hydro_plot(
view,
hydro_legacy_code,
(snapshot_size, snapshot_size),
base_output_file_name + "_hydro_image{0:=03}.png".format(i_step)
)
hydro_legacy_code.gas_particles.new_channel_to(all_sph_particles).copy_attributes(
['mass', 'x','y','z', 'vx','vy','vz', 'u'])
center_of_mass = all_sph_particles.center_of_mass().as_quantity_in(units.RSun)
center_of_mass_velocity = all_sph_particles.center_of_mass_velocity().as_quantity_in(units.km / units.s)
print
print "center_of_mass:", center_of_mass
print "center_of_mass_velocity:", center_of_mass_velocity
all_sph_particles.position -= center_of_mass
sph_midpoints = all_sph_particles.position.lengths()
energy_plot(
times,
kinetic_energies, potential_energies, thermal_energies,
base_output_file_name+"_energy_evolution.png"
)
thermal_energy_plot(
times,
thermal_energies,
base_output_file_name+"_thermal_energy_evolution.png"
)
composition_comparison_plot(
midpoints, composition[0],
sph_midpoints, all_sph_particles.h1,
base_output_file_name+"_composition_h1.png"
)
internal_energy_comparison_plot(
midpoints, specific_internal_energy,
sph_midpoints, all_sph_particles.u,
base_output_file_name+"_new_u.png"
)
hydro_plot(
[-2.0, 2.0, -2.0, 2.0] | units.RSun,
hydro_legacy_code,
(100, 100),
base_output_file_name + "_hydro_image.png"
)
hydro_legacy_code.stop()
print "All done!\n"
def head_on_stellar_merger(
masses=[0.3, 3.0] | units.MSun,
star_age=310.0 | units.Myr,
maximally_evolved_stars=False,
initial_separation=4.0 | units.RSun,
angle=numpy.pi / 3,
initial_speed=3000.0 | units.km / units.s,
initial_speed_perpendicular=30.0 | units.km / units.s,
number_of_sph_particles=1000,
t_end=1.0e4 | units.s,
sph_code=Fi,
steps_per_snapshot=4,
snapshot_size=100,
use_stored_stellar_models=True
):
"""
masses: Mass of the two stars
star_age: Initial age of the stars (if maximally_evolved_stars is False)
maximally_evolved_stars: Evolve stars as far as the Stellar Evolution code
can get
number_of_sph_particles: Total number of particles of both stars, divided
according to their masses
t_end: (Physical, not computational) duration of the hydrodynamics
simulation
sph_code: Code to use for the hydrodynamics simulation
steps_per_snapshot: A hydroplot snapshot is generated each time after this
many steps (0 or None means no snapshots)
snapshot_size: Size of the snapshot in pixels along one dimension
use_stored_stellar_models: Flag to use previously stored stellar model
files (for speed-up).
"""
# Convert some of the input parameters to string, for use in output file
# names:
n_string = "n" + ("%1.0e" % (number_of_sph_particles)
).replace("+0", "").replace("+", "")
t_end_string = "t" + ("%1.0e" % (t_end.value_in(units.s))
).replace("+0", "").replace("+", "")
masses_string = (
"m1_"
+ (
"%0.3e" % (masses[0].value_in(units.MSun))
).replace("+0", "").replace("+", "")
+ "_m2_"
+ (
"%0.3e" % (masses[1].value_in(units.MSun))
).replace("+0", "").replace("+", "")
)
if maximally_evolved_stars:
star_age_string = "a_max"
else:
star_age_string = "a" + \
("%0.3e" % (star_age.value_in(units.Myr))).replace(
"+0", "").replace("+", "")
base_output_file_name = os.path.join(
get_path_to_results(), "stellar_merger_"+n_string+"_"+t_end_string)
pickle_file_1 = os.path.join(get_path_to_results(
), "stellar_merger_"+masses_string+"_"+star_age_string+"_1.pkl")
pickle_file_2 = os.path.join(get_path_to_results(
), "stellar_merger_"+masses_string+"_"+star_age_string+"_2.pkl")
if not use_stored_stellar_models or not (os.path.exists(pickle_file_1) and os.path.exists(pickle_file_2)):
stars = Particles(2)
stars.mass = masses
try:
stellar_evolution = MESA()
stellar_evolution.initialize_code()
except:
print("MESA was not built. Returning.")
return
stellar_evolution.commit_parameters()
stellar_evolution.particles.add_particles(stars)
stellar_evolution.commit_particles()
if maximally_evolved_stars:
try:
while True:
stellar_evolution.evolve_model()
except AmuseException as exception:
print(exception)
else:
stellar_evolution.evolve_model(star_age)
if os.path.exists(pickle_file_1):
print("Could not save stellar model 1: file already exists.")
else:
pickle_stellar_model(stellar_evolution.particles[0], pickle_file_1)
print("Stellar model 1 saved at:", pickle_file_1)
if os.path.exists(pickle_file_2):
print("Could not save stellar model 2: file already exists.")
else:
pickle_stellar_model(stellar_evolution.particles[1], pickle_file_2)
print("Stellar model 2 saved at:", pickle_file_2)
stellar_evolution.stop()
model_1 = StellarModel2SPH(None, None, pickle_file=pickle_file_1)
model_2 = StellarModel2SPH(None, None, pickle_file=pickle_file_2)
model_1.unpickle_stellar_structure()
model_2.unpickle_stellar_structure()
composition = model_2.composition_profile
midpoints = model_2.midpoints_profile[1:-1]
specific_internal_energy = model_2.specific_internal_energy_profile
number_of_sph_particles_1 = int(
round(
number_of_sph_particles
* (model_1.mass / (model_1.mass + model_2.mass))
)
)
number_of_sph_particles_2 = (
number_of_sph_particles
- number_of_sph_particles_1
)
print("Creating initial conditions from a MESA stellar evolution model:")
print(
model_1.mass,
"star consisting of",
number_of_sph_particles_1,
"particles."
)
sph_particles_1 = convert_stellar_model_to_SPH(
None,
number_of_sph_particles_1,
seed=12345,
pickle_file = pickle_file_1
).gas_particles
print(
model_2.mass,
"star consisting of",
number_of_sph_particles_2,
"particles."
)
sph_particles_2 = convert_stellar_model_to_SPH(
None,
number_of_sph_particles_2,
pickle_file=pickle_file_2
).gas_particles
initial_separation += model_1.radius + model_2.radius
sph_particles_2.x += numpy.cos(angle) * initial_separation
sph_particles_2.y += numpy.sin(angle) * initial_separation
sph_particles_1.vx += (
numpy.cos(angle) * initial_speed
- numpy.sin(angle) * initial_speed_perpendicular
)
sph_particles_1.vy += (
numpy.cos(angle) * initial_speed_perpendicular
+ numpy.sin(angle) * initial_speed
)
view = (
[-0.5, 0.5, -0.5, 0.5]
* (initial_separation + model_1.radius + model_2.radius)
)
all_sph_particles = ParticlesSuperset([sph_particles_1, sph_particles_2])
all_sph_particles.move_to_center()
unit_converter = ConvertBetweenGenericAndSiUnits(
1.0 | units.RSun, constants.G, t_end)
hydro_legacy_code = sph_code(unit_converter)
n_steps = 100
hydro_legacy_code.parameters.n_smooth = 96
try:
hydro_legacy_code.parameters.timestep = t_end / n_steps
except Exception as exc:
if "parameter is read-only" not in str(exc):
raise
hydro_legacy_code.gas_particles.add_particles(all_sph_particles)
times = [] | units.Myr
kinetic_energies = [] | units.J
potential_energies = [] | units.J
thermal_energies = [] | units.J
print("Evolving to:", t_end)
for time, i_step in [(i*t_end/n_steps, i) for i in range(1, n_steps+1)]:
hydro_legacy_code.evolve_model(time)
times.append(time)
kinetic_energies.append(hydro_legacy_code.kinetic_energy)
potential_energies.append(hydro_legacy_code.potential_energy)
thermal_energies.append(hydro_legacy_code.thermal_energy)
if steps_per_snapshot and (not i_step % steps_per_snapshot):
hydro_plot(
view,
hydro_legacy_code,
(snapshot_size, snapshot_size),
base_output_file_name +
"_hydro_image{0:=03}.png".format(i_step)
)
hydro_legacy_code.gas_particles.new_channel_to(
all_sph_particles
).copy_attributes(
['mass', 'x', 'y', 'z', 'vx', 'vy', 'vz', 'u']
)
center_of_mass = all_sph_particles.center_of_mass(
).as_quantity_in(units.RSun)
center_of_mass_velocity = all_sph_particles.center_of_mass_velocity(
).as_quantity_in(units.km / units.s)
print()
print("center_of_mass:", center_of_mass)
print("center_of_mass_velocity:", center_of_mass_velocity)
all_sph_particles.position -= center_of_mass
sph_midpoints = all_sph_particles.position.lengths()
energy_plot(
times,
kinetic_energies, potential_energies, thermal_energies,
base_output_file_name+"_energy_evolution.png"
)
thermal_energy_plot(
times,
thermal_energies,
base_output_file_name+"_thermal_energy_evolution.png"
)
composition_comparison_plot(
midpoints, composition[0],
sph_midpoints, all_sph_particles.h1,
base_output_file_name+"_composition_h1.png"
)
internal_energy_comparison_plot(
midpoints, specific_internal_energy,
sph_midpoints, all_sph_particles.u,
base_output_file_name+"_new_u.png"
)
hydro_plot(
[-2.0, 2.0, -2.0, 2.0] | units.RSun,
hydro_legacy_code,
(100, 100),
base_output_file_name + "_hydro_image.png"
)
hydro_legacy_code.stop()
print("All done!\n")
