############################################################################### # This file is part of SWIFT. # Copyright (c) 2016 Stefan Arridge (stefan.arridge@durham.ac.uk) # # This program is free software: you can redistribute it and/or modify # it under the terms of the GNU Lesser General Public License as published # by the Free Software Foundation, either version 3 of the License, or # (at your option) any later version. # # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. # # You should have received a copy of the GNU Lesser General Public License # along with this program. If not, see . # ############################################################################## import numpy as np import h5py as h5 import matplotlib matplotlib.use("Agg") from pylab import * import sys n_snaps = int(sys.argv[1]) # some constants OMEGA = 0.3 # Cosmological matter fraction at z = 0 PARSEC_IN_CGS = 3.0856776e18 KM_PER_SEC_IN_CGS = 1.0e5 CONST_G_CGS = 6.672e-8 h = 0.67777 # hubble parameter gamma = 5.0 / 3.0 eta = 1.2349 H_0_cgs = 100.0 * h * KM_PER_SEC_IN_CGS / (1.0e6 * PARSEC_IN_CGS) # read some header/parameter information from the first snapshot filename = "Hydrostatic_0000.hdf5" f = h5.File(filename, "r") params = f["Parameters"] unit_mass_cgs = float(params.attrs["InternalUnitSystem:UnitMass_in_cgs"]) unit_length_cgs = float(params.attrs["InternalUnitSystem:UnitLength_in_cgs"]) unit_velocity_cgs = float(params.attrs["InternalUnitSystem:UnitVelocity_in_cgs"]) unit_time_cgs = unit_length_cgs / unit_velocity_cgs v_c = float(params.attrs["IsothermalPotential:vrot"]) v_c_cgs = v_c * unit_velocity_cgs header = f["Header"] N = header.attrs["NumPart_Total"][0] box_centre = np.array(header.attrs["BoxSize"]) # calculate r_vir and M_vir from v_c r_vir_cgs = v_c_cgs / (10.0 * H_0_cgs * np.sqrt(OMEGA)) M_vir_cgs = r_vir_cgs * v_c_cgs ** 2 / CONST_G_CGS potential_energy_array = [] internal_energy_array = [] kinetic_energy_array = [] time_array_cgs = [] for i in range(n_snaps): filename = "Hydrostatic_%04d.hdf5" % i f = h5.File(filename, "r") coords_dset = f["PartType0/Coordinates"] coords = np.array(coords_dset) # translate coords by centre of box header = f["Header"] snap_time = header.attrs["Time"] snap_time_cgs = snap_time * unit_time_cgs time_array_cgs = np.append(time_array_cgs, snap_time_cgs) coords[:, 0] -= box_centre[0] / 2.0 coords[:, 1] -= box_centre[1] / 2.0 coords[:, 2] -= box_centre[2] / 2.0 radius = np.sqrt(coords[:, 0] ** 2 + coords[:, 1] ** 2 + coords[:, 2] ** 2) radius_cgs = radius * unit_length_cgs radius_over_virial_radius = radius_cgs / r_vir_cgs r = radius_over_virial_radius total_potential_energy = np.sum(v_c ** 2 * np.log(r)) potential_energy_array = np.append(potential_energy_array, total_potential_energy) vels_dset = f["PartType0/Velocities"] vels = np.array(vels_dset) speed_squared = vels[:, 0] ** 2 + vels[:, 1] ** 2 + vels[:, 2] ** 2 total_kinetic_energy = 0.5 * np.sum(speed_squared) kinetic_energy_array = np.append(kinetic_energy_array, total_kinetic_energy) u_dset = f["PartType0/InternalEnergy"] u = np.array(u_dset) total_internal_energy = np.sum(u) internal_energy_array = np.append(internal_energy_array, total_internal_energy) # put energies in units of v_c^2 and rescale by number of particles pe = potential_energy_array / (N * v_c ** 2) ke = kinetic_energy_array / (N * v_c ** 2) ie = internal_energy_array / (N * v_c ** 2) te = pe + ke + ie dyn_time_cgs = r_vir_cgs / v_c_cgs time_array = time_array_cgs / dyn_time_cgs figure() plot(time_array, ke, label="Kinetic Energy") plot(time_array, pe, label="Potential Energy") plot(time_array, ie, label="Internal Energy") plot(time_array, te, label="Total Energy") legend(loc="lower right") xlabel(r"$t / t_{dyn}$") ylabel(r"$E / v_c^2$") title(r"$%d \, \, \mathrm{particles} \,,\, v_c = %.1f \, \mathrm{km / s}$" % (N, v_c)) ylim((-2, 2)) savefig("energy_conservation.png", format="png")