def _gravitationally_bound(clump,
use_thermal_energy=True,
use_particles=True,
truncate=True):
"True if clump is gravitationally bound."
use_particles &= \
("all", "particle_mass") in clump.data.ds.field_info
bulk_velocity = clump.quantities.bulk_velocity(use_particles=use_particles)
kinetic = 0.5 * (clump["gas", "cell_mass"] * (
(bulk_velocity[0] - clump["gas", "velocity_x"])**2 +
(bulk_velocity[1] - clump["gas", "velocity_y"])**2 +
(bulk_velocity[2] - clump["gas", "velocity_z"])**2)).sum()
if use_thermal_energy:
kinetic += (clump["gas", "cell_mass"] *
clump["gas", "thermal_energy"]).sum()
if use_particles:
kinetic += 0.5 * (clump["all", "particle_mass"] * (
(bulk_velocity[0] - clump["all", "particle_velocity_x"])**2 +
(bulk_velocity[1] - clump["all", "particle_velocity_y"])**2 +
(bulk_velocity[2] - clump["all", "particle_velocity_z"])**2)
).sum()
potential = clump.data.ds.quan(
G * gravitational_binding_energy(
clump["gas", "cell_mass"].in_cgs(), clump["index", "x"].in_cgs(),
clump["index", "y"].in_cgs(), clump["index", "z"].in_cgs(),
truncate, (kinetic / G).in_cgs()),
kinetic.in_cgs().units)
if truncate and potential >= kinetic:
return True
if use_particles:
potential += clump.data.ds.quan(
G * gravitational_binding_energy(
clump["all", "particle_mass"].in_cgs(),
clump["all", "particle_position_x"].in_cgs(),
clump["all", "particle_position_y"].in_cgs(),
clump["all", "particle_position_z"].in_cgs(), truncate,
((kinetic - potential) / G).in_cgs()),
kinetic.in_cgs().units)
return potential >= kinetic
def _future_bound(
clump,
use_thermal_energy=True,
truncate=True,
include_cooling=True):
"""
True if clump has negative total energy. This considers gas kinetic
energy, thermal energy, and radiative losses over a free-fall time
against gravitational potential energy of the gas and collisionless
particle system.
"""
num_threads = int(os.environ.get('OMP_NUM_THREADS', 1))
if clump["gas", "cell_mass"].size <= 1:
mylog.info("Clump has only one cell.")
return False
bulk_velocity = clump.quantities.bulk_velocity(
use_particles=False)
kinetic = 0.5 * (clump["gas", "cell_mass"] *
((bulk_velocity[0] - clump["gas", "velocity_x"])**2 +
(bulk_velocity[1] - clump["gas", "velocity_y"])**2 +
(bulk_velocity[2] - clump["gas", "velocity_z"])**2)).sum()
mylog.info("Kinetic energy: %e erg." %
kinetic.in_units("erg"))
if use_thermal_energy:
cooling_loss = clump.data.ds.quan(0.0, "erg")
thermal = (clump["gas", "cell_mass"] *
clump["gas", "thermal_energy"]).sum()
mylog.info("Thermal energy: %e erg." %
thermal.in_units("erg"))
if include_cooling:
# divide by sqrt(2) since t_ff = t_dyn / sqrt(2)
cooling_loss = \
(clump["gas", "cell_mass"] *
clump["gas", "dynamical_time"] *
clump["gas", "thermal_energy"] /
clump["gas", "cooling_time"]).sum() / np.sqrt(2)
mylog.info("Cooling loss: %e erg." %
cooling_loss.in_units("erg"))
thermal -= np.abs(cooling_loss)
kinetic += thermal
kinetic = max(kinetic, clump.data.ds.quan(0.0, "erg"))
mylog.info("Available energy: %e erg." %
kinetic.in_units("erg"))
m = np.concatenate([clump["gas", "cell_mass"].in_cgs(),
clump["all", "particle_mass"].in_cgs()])
px = np.concatenate([clump["index", "x"].in_cgs(),
clump["all", "particle_position_x"].in_cgs()])
py = np.concatenate([clump["index", "y"].in_cgs(),
clump["all", "particle_position_y"].in_cgs()])
pz = np.concatenate([clump["index", "z"].in_cgs(),
clump["all", "particle_position_z"].in_cgs()])
potential = clump.data.ds.quan(
G * gravitational_binding_energy(
m, px, py, pz,
truncate, (kinetic / G).in_cgs(),
num_threads=num_threads),
kinetic.in_cgs().units)
mylog.info("Potential energy: %e erg." %
potential.to('erg'))
return potential >= kinetic
def _gravitationally_bound(clump,
use_thermal_energy=True,
use_particles=True,
truncate=True,
num_threads=0):
"True if clump is gravitationally bound."
use_particles &= ("all", "particle_mass") in clump.data.ds.field_info
bulk_velocity = clump.quantities.bulk_velocity(use_particles=use_particles)
kinetic = (0.5 *
(clump["gas", "cell_mass"] *
((bulk_velocity[0] - clump["gas", "velocity_x"])**2 +
(bulk_velocity[1] - clump["gas", "velocity_y"])**2 +
(bulk_velocity[2] - clump["gas", "velocity_z"])**2)).sum())
if use_thermal_energy:
kinetic += (clump["gas", "cell_mass"] *
clump["gas", "thermal_energy"]).sum()
if use_particles:
kinetic += (0.5 * (clump["all", "particle_mass"] * (
(bulk_velocity[0] - clump["all", "particle_velocity_x"])**2 +
(bulk_velocity[1] - clump["all", "particle_velocity_y"])**2 +
(bulk_velocity[2] - clump["all", "particle_velocity_z"])**2)
).sum())
if use_particles:
m = np.concatenate([
clump["gas", "cell_mass"].in_cgs(),
clump["all", "particle_mass"].in_cgs()
])
px = np.concatenate([
clump["index", "x"].in_cgs(),
clump["all", "particle_position_x"].in_cgs()
])
py = np.concatenate([
clump["index", "y"].in_cgs(),
clump["all", "particle_position_y"].in_cgs()
])
pz = np.concatenate([
clump["index", "z"].in_cgs(),
clump["all", "particle_position_z"].in_cgs()
])
else:
m = clump["gas", "cell_mass"].in_cgs()
px = clump["index", "x"].in_cgs()
py = clump["index", "y"].in_cgs()
pz = clump["index", "z"].in_cgs()
potential = clump.data.ds.quan(
G * gravitational_binding_energy(m,
px,
py,
pz,
truncate, (kinetic / G).in_cgs(),
num_threads=num_threads),
kinetic.in_cgs().units,
)
if truncate and potential >= kinetic:
return True
return potential >= kinetic