def test2(self): print "Testing MI6 parameters" instance = MI6(self.default_converter, **default_options) instance.initialize_code() self.assertEquals( instance.parameters.epsilon_squared, instance.unit_converter.to_si(0.0 | nbody_system.length**2)) self.assertEquals(instance.parameters.timestep_parameter, 0.1) for par, value in [ ('epsilon_squared_star_star', 0.0 | nbody_system.length**2), ('epsilon_squared_star_blackhole', 0.0 | nbody_system.length**2), ('epsilon_squared_blackhole_blackhole', 0.0 | nbody_system.length**2), ('initial_timestep_parameter', 1.0e-4), ('timestep_parameter_stars', 0.1), ('timestep_parameter_supermassive_black_holes', 0.4), ('timestep_parameter_intermediate_mass_black_holes', 0.4), ('max_relative_energy_error', 5.0e-5), ('maximum_timestep', 1.0 / 1024.0 | nbody_system.time), ('smbh_mass', 1.0 | nbody_system.mass), ('lightspeed', 1.0 | nbody_system.speed) ]: self.assertEquals(instance.unit_converter.to_si(value), getattr(instance.parameters, par)) if hasattr(value, 'unit'): new_value = 3.0 | value.unit else: new_value = 3.0 setattr(instance.parameters, par, new_value) self.assertEquals(instance.unit_converter.to_si(new_value), getattr(instance.parameters, par)) # epsilon_squared is an alias for epsilon_squared_star_star, so epsilon_squared also has become 3: self.assertEquals( instance.parameters.epsilon_squared, instance.unit_converter.to_si(3.0 | nbody_system.length**2)) instance.parameters.epsilon_squared = 0.1 | nbody_system.length**2 self.assertEquals( instance.parameters.epsilon_squared, instance.unit_converter.to_si(0.1 | nbody_system.length**2)) # timestep_parameter is an alias for timestep_parameter_stars, so timestep_parameter also has become 3: self.assertEquals(instance.parameters.timestep_parameter, 3.0) instance.parameters.timestep_parameter = 0.01 self.assertEquals(instance.parameters.timestep_parameter, 0.01) self.assertEquals(instance.parameters.include_smbh, False) instance.parameters.include_smbh = True self.assertEquals(instance.parameters.include_smbh, True) self.assertEquals(instance.parameters.calculate_postnewtonian, True) instance.parameters.calculate_postnewtonian = False self.assertEquals(instance.parameters.calculate_postnewtonian, False) self.assertEquals(instance.parameters.drink, "Vodka martini. Shaken, not stirred.") instance.stop()
def test9(self): print "Testing MI6 evolve_model and getters energy, plummer sphere, no SMBH" converter = nbody_system.nbody_to_si(1.0e2 | units.MSun, 1.0 | units.parsec) instance = MI6(converter, **default_options) instance.initialize_code() instance.parameters.smbh_mass = 0.0 | units.MSun instance.commit_parameters() numpy.random.seed(987654321) instance.particles.add_particles( new_plummer_model(100, convert_nbody=converter)) instance.commit_particles() kinetic_energy = instance.kinetic_energy potential_energy = instance.potential_energy self.assertAlmostRelativeEqual(kinetic_energy, 2.12292810174e+37 | units.J, 10) self.assertAlmostRelativeEqual(potential_energy, -4.33511391248e+37 | units.J, 10) initial_total_energy = kinetic_energy + potential_energy instance.evolve_model(0.1 | nbody_system.time) kinetic_energy = instance.kinetic_energy potential_energy = instance.potential_energy self.assertAlmostRelativeEqual(kinetic_energy, 2.13633848369e+37 | units.J, 5) self.assertAlmostRelativeEqual(potential_energy, -4.34851806763e+37 | units.J, 5) self.assertAlmostRelativeEqual(potential_energy + kinetic_energy, initial_total_energy, 5) instance.cleanup_code() instance.stop()
def test7(self): print "Testing effect of MI6 parameter epsilon_squared" converter = nbody_system.nbody_to_si(1.0 | units.MSun, 1.0 | units.AU) particles = self.new_sun_earth_system() particles.rotate(0.0, 0.0, -math.pi / 4) particles.move_to_center() tan_initial_direction = particles[1].vy / particles[1].vx self.assertAlmostEquals(tan_initial_direction, math.tan(math.pi / 4)) tan_final_direction = [] for log_eps2 in range(-9, 10, 2): instance = MI6(converter, **default_options) instance.initialize_code() instance.parameters.epsilon_squared = 10.0**log_eps2 | units.AU**2 instance.parameters.smbh_mass = 0.0 | units.MSun instance.commit_parameters() instance.particles.add_particles(particles) instance.commit_particles() instance.evolve_model(0.25 | units.yr) tan_final_direction.append(instance.particles[1].velocity[1] / instance.particles[1].velocity[0]) instance.cleanup_code() instance.stop() # Small values of epsilon_squared should result in normal earth-sun dynamics: rotation of 90 degrees self.assertAlmostEquals(tan_final_direction[0], math.tan(3 * math.pi / 4.0), 2) # Large values of epsilon_squared should result in ~ no interaction self.assertAlmostEquals(tan_final_direction[-1], tan_initial_direction, 2) # Outcome is most sensitive to epsilon_squared when epsilon_squared = d(earth, sun)^2 delta = [ abs(tan_final_direction[i + 1] - tan_final_direction[i]) for i in range(len(tan_final_direction) - 1) ] self.assertEquals(delta[len(tan_final_direction) // 2 - 1], max(delta))
def test1(self): print "Testing MI6 initialization" instance = MI6(self.default_converter, **default_options) instance.initialize_code() instance.commit_parameters() instance.cleanup_code() instance.stop()
def new_coupled_system(hydro, binary_system, t_end, n_steps): kick_from_hydro = CalculateFieldForParticles(particles=hydro.particles, gravity_constant=constants.G) kick_from_hydro.smoothing_length_squared = 100 | units.RSun**2 unit_converter = nbody_system.nbody_to_si(binary_system.particles.total_mass(), t_end) kicker_code = MI6(unit_converter, redirection='file', redirect_file='kicker_code_mi6_out.log') kicker_code.parameters.epsilon_squared = 100 | units.RSun**2 kick_from_binary = CalculateFieldForCodesUsingReinitialize(kicker_code, (binary_system,)) coupled_system = Bridge(timestep=(t_end / (2 * n_steps)), verbose=False, use_threading=True) coupled_system.add_system(binary_system, (kick_from_hydro,), False) coupled_system.add_system(hydro, (kick_from_binary,), False) return coupled_system
def test8(self): print "Testing MI6 get_gravity_at_point and get_potential_at_point" instance = MI6(**default_options) instance.initialize_code() instance.parameters.epsilon_squared = 0.0 | nbody_system.length**2 instance.parameters.smbh_mass = 0.0 | nbody_system.mass particles = Particles(2) particles.mass = 1.0 | nbody_system.mass particles.radius = 0.0 | nbody_system.length particles.position = [[0.0, 0.0, 0.0], [2.0, 0.0, 0.0] ] | nbody_system.length particles.velocity = [[0.0, 0.0, 0.0], [0.0, 0.0, 0.0] ] | nbody_system.speed instance.particles.add_particles(particles) zero = 0.0 | nbody_system.length fx, fy, fz = instance.get_gravity_at_point(zero, 1.0 | nbody_system.length, zero, zero) self.assertAlmostEqual(fx, 0.0 | nbody_system.acceleration) self.assertAlmostEqual(fy, 0.0 | nbody_system.acceleration) self.assertAlmostEqual(fz, 0.0 | nbody_system.acceleration) for x in (0.25, 0.5, 0.75): x0 = x | nbody_system.length x1 = (2.0 - x) | nbody_system.length potential0 = instance.get_potential_at_point(zero, x0, zero, zero) potential1 = instance.get_potential_at_point(zero, x1, zero, zero) fx0, fy0, fz0 = instance.get_gravity_at_point(zero, x0, zero, zero) fx1, fy1, fz1 = instance.get_gravity_at_point(zero, x1, zero, zero) self.assertAlmostEqual(fy0, 0.0 | nbody_system.acceleration) self.assertAlmostEqual(fz0, 0.0 | nbody_system.acceleration) self.assertAlmostEqual(fy1, 0.0 | nbody_system.acceleration) self.assertAlmostEqual(fz1, 0.0 | nbody_system.acceleration) self.assertAlmostEqual(fx0, -1.0 * fx1) fx = (-1.0 / (x0**2) + 1.0 / (x1**2)) * (1.0 | nbody_system.length**3 / nbody_system.time**2) self.assertAlmostEqual(fx, fx0) self.assertAlmostEqual(potential0, potential1) instance.stop()
def test11(self): print "Testing MI6 properties" numpy.random.seed(12345) particles = new_plummer_model(100, do_scale=True) particles.position += [1, 2, 3] | nbody_system.length cluster_velocity = [4, 5, 6] | nbody_system.speed particles.velocity += cluster_velocity external_kinetic_energy = ( 0.5 | nbody_system.mass) * cluster_velocity.length_squared() instance = MI6(**default_options) instance.particles.add_particles(particles) kinetic_energy = instance.kinetic_energy - external_kinetic_energy potential_energy = instance.potential_energy self.assertAlmostRelativeEqual(kinetic_energy, 0.25 | nbody_system.energy, 10) self.assertAlmostRelativeEqual(potential_energy, -0.5 | nbody_system.energy, 10) self.assertAlmostRelativeEqual(instance.total_mass, 1.0 | nbody_system.mass, 10) self.assertAlmostRelativeEqual(instance.center_of_mass_position, [1, 2, 3] | nbody_system.length, 10) self.assertAlmostRelativeEqual(instance.center_of_mass_velocity, [4, 5, 6] | nbody_system.speed, 10) initial_total_energy = kinetic_energy + potential_energy instance.evolve_model(0.1 | nbody_system.time) self.assertAlmostRelativeEqual(instance.model_time, 0.1 | nbody_system.time) kinetic_energy = instance.kinetic_energy - external_kinetic_energy potential_energy = instance.potential_energy self.assertAlmostRelativeEqual(kinetic_energy + potential_energy, -0.25 | nbody_system.energy, 3) self.assertAlmostRelativeEqual(instance.total_mass, 1.0 | nbody_system.mass, 3) self.assertAlmostRelativeEqual(instance.center_of_mass_position, [1.4, 2.5, 3.6] | nbody_system.length, 3) self.assertAlmostRelativeEqual(instance.center_of_mass_velocity, [4, 5, 6] | nbody_system.speed, 3) instance.cleanup_code() instance.stop()
def test3(self): print "Testing MI6 particles" instance = MI6(self.default_converter, **default_options) instance.initialize_code() instance.commit_parameters() instance.particles.add_particles(self.new_sun_earth_system()) instance.commit_particles() self.assertAlmostEquals(instance.particles.mass, [1.0, 3.0037e-6] | units.MSun) self.assertAlmostEquals(instance.particles.radius, 1.0 | units.RSun) self.assertAlmostEquals(instance.particles.position, [[0.0, 0.0, 0.0], [1.0, 0.0, 0.0]] | units.AU) self.assertAlmostEquals(instance.particles.velocity, [[0.0, 0.0, 0.0], [0.0, 29.7885, 0.0]] | units.km / units.s, 3) instance.cleanup_code() instance.stop()
def test4(self): print "Testing MI6 evolve_model, 2 particles orbiting the SMBH" particles = Particles(2) particles.mass = 1.0 | units.MSun particles.radius = 1.0 | units.RSun particles.position = [[0.0, 0.0, 0.0], [2.0, 0.0, 0.0]] | units.AU particles.velocity = [[0.0, 0.0, 0.0], [0.0, 0.0, 0.0] ] | units.km / units.s particles[1].vy = ((constants.G * (10001.0 | units.MSun) / (1.0 | units.AU)).sqrt() + (constants.G * (10000.0 | units.MSun) / (1.0 | units.AU)).sqrt()) particles.move_to_center() print particles instance = MI6(self.default_converter, **default_options) instance.initialize_code() instance.parameters.include_smbh = True instance.parameters.lightspeed = constants.c instance.commit_parameters() instance.particles.add_particles(particles) instance.commit_particles() primary = instance.particles[0] P = 2 * math.pi * primary.x / primary.vy P_corrected = (P) * (2.0 / (1.0 + math.sqrt(1.0001))) position_at_start = primary.position.x instance.evolve_model(P_corrected / 4.0) self.assertAlmostRelativeEqual(position_at_start, primary.position.y, 3) instance.evolve_model(P_corrected / 2.0) self.assertAlmostRelativeEqual(position_at_start, -primary.position.x, 3) instance.evolve_model(P_corrected) self.assertAlmostRelativeEqual(position_at_start, primary.position.x, 3) instance.cleanup_code() instance.stop()
def test5(self): print "Testing MI6 evolve_model, 2 particles, no SMBH" particles = Particles(2) particles.mass = 1.0 | units.MSun particles.radius = 1.0 | units.RSun particles.position = [[0.0, 0.0, 0.0], [2.0, 0.0, 0.0]] | units.AU particles.velocity = [[0.0, 0.0, 0.0], [0.0, 0.0, 0.0] ] | units.km / units.s particles[1].vy = (constants.G * (2.0 | units.MSun) / (2.0 | units.AU)).sqrt() particles.move_to_center() print particles converter = nbody_system.nbody_to_si(1.0 | units.MSun, 1.0 | units.AU) instance = MI6(converter, **default_options) instance.initialize_code() instance.parameters.smbh_mass = 0.0 | units.MSun instance.commit_parameters() instance.particles.add_particles(particles) instance.commit_particles() primary = instance.particles[0] P = 2 * math.pi * primary.x / primary.vy position_at_start = primary.position.x instance.evolve_model(P / 4.0) self.assertAlmostRelativeEqual(position_at_start, primary.position.y, 3) instance.evolve_model(P / 2.0) self.assertAlmostRelativeEqual(position_at_start, -primary.position.x, 3) instance.evolve_model(P) self.assertAlmostRelativeEqual(position_at_start, primary.position.x, 3) instance.cleanup_code() instance.stop()
def test6(self): print "Testing MI6 evolve_model, earth-sun system, no SMBH" converter = nbody_system.nbody_to_si(1.0 | units.MSun, 1.0 | units.AU) instance = MI6(converter, **default_options) instance.initialize_code() instance.parameters.smbh_mass = 0.0 | units.MSun instance.commit_parameters() instance.particles.add_particles(self.new_sun_earth_system()) instance.commit_particles() earth = instance.particles[1] position_at_start = earth.position.x instance.evolve_model(0.25 | units.yr) self.assertAlmostRelativeEqual(position_at_start, earth.position.y, 3) instance.evolve_model(0.5 | units.yr) self.assertAlmostRelativeEqual(position_at_start, -earth.position.x, 3) instance.evolve_model(1.0 | units.yr) self.assertAlmostRelativeEqual(position_at_start, earth.position.x, 3) instance.cleanup_code() instance.stop()
def test10(self): print "Testing MI6 collision_detection" particles = Particles(7) particles.mass = 0.00000001 | nbody_system.mass particles.radius = 0.0001 | nbody_system.length particles.x = [-101.0, -100.0, -0.5, 0.5, 100.0, 101.0, 104.0 ] | nbody_system.length particles.y = 0 | nbody_system.length particles.z = 0 | nbody_system.length particles.velocity = [[2, 0, 0], [-2, 0, 0] ] * 3 + [[-4, 0, 0]] | nbody_system.speed instance = MI6(**default_options) instance.initialize_code() instance.parameters.set_defaults() instance.particles.add_particles(particles) collisions = instance.stopping_conditions.collision_detection collisions.enable() instance.evolve_model(1.0 | nbody_system.time) self.assertTrue(collisions.is_set()) self.assertAlmostEquals( instance.model_time, -(particles[0].x - particles[1].x) / (particles[0].vx - particles[1].vx), 3) self.assertEquals(len(collisions.particles(0)), 3) self.assertEquals(len(collisions.particles(1)), 3) self.assertEquals( len(particles - collisions.particles(0) - collisions.particles(1)), 1) self.assertEquals( abs(collisions.particles(0).x - collisions.particles(1).x) < (collisions.particles(0).radius + collisions.particles(1).radius), [True, True, True]) sticky_merged = Particles(len(collisions.particles(0))) sticky_merged.mass = collisions.particles( 0).mass + collisions.particles(1).mass sticky_merged.radius = collisions.particles(0).radius for p1, p2, merged in zip(collisions.particles(0), collisions.particles(1), sticky_merged): merged.position = (p1 + p2).center_of_mass() merged.velocity = (p1 + p2).center_of_mass_velocity() print instance.model_time print instance.particles instance.particles.remove_particles( collisions.particles(0) + collisions.particles(1)) instance.particles.add_particles(sticky_merged) instance.evolve_model(1.0 | nbody_system.time) print print instance.model_time print instance.particles self.assertTrue(collisions.is_set()) self.assertAlmostEquals( instance.model_time, -(particles[6].x - 0.5 * (particles[4].x + particles[5].x)) / particles[6].vx, 3) self.assertEquals(len(collisions.particles(0)), 1) self.assertEquals(len(collisions.particles(1)), 1) self.assertEquals( len(instance.particles - collisions.particles(0) - collisions.particles(1)), 2) self.assertEquals( abs(collisions.particles(0).x - collisions.particles(1).x) < (collisions.particles(0).radius + collisions.particles(1).radius), [True]) instance.stop()