makeIC.py

###############################################################################
 # This file is part of SWIFT.
 # Copyright (c) 2016 Matthieu Schaller (matthieu.schaller@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 <http://www.gnu.org/licenses/>.
 # 
 ##############################################################################

import h5py
from numpy import *

# Generates a swift IC file for the 1D Noh problem test in a periodic box

# Parameters
numPart = 1001
gamma = 5./3.      # Gas adiabatic index
rho0 = 1.          # Background density
P0 = 1.e-6         # Background pressure
fileName = "noh.hdf5" 

#---------------------------------------------------
coords = zeros((numPart, 3))
h = zeros(numPart)
vol = 2.

for i in range(numPart):
    coords[i,0] = i * vol/numPart + vol/(2.*numPart)
    h[i] = 1.2348 * vol / numPart

# Generate extra arrays
v = zeros((numPart, 3))
ids = linspace(1, numPart, numPart)
m = zeros(numPart)
u = zeros(numPart)

m[:] = rho0 * vol / numPart    
u[:] = P0 / (rho0 * (gamma - 1))
v[coords[:,0]<vol/2. ,0] = 1
v[coords[:,0]>vol/2. ,0] = -1

#--------------------------------------------------

#File
file = h5py.File(fileName, 'w')

# Header
grp = file.create_group("/Header")
grp.attrs["BoxSize"] = [vol, vol, vol]
grp.attrs["NumPart_Total"] =  [numPart, 0, 0, 0, 0, 0]
grp.attrs["NumPart_Total_HighWord"] = [0, 0, 0, 0, 0, 0]
grp.attrs["NumPart_ThisFile"] = [numPart, 0, 0, 0, 0, 0]
grp.attrs["Time"] = 0.0
grp.attrs["NumFilesPerSnapshot"] = 1
grp.attrs["MassTable"] = [0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
grp.attrs["Flag_Entropy_ICs"] = 0
grp.attrs["Dimension"] = 1

#Runtime parameters
grp = file.create_group("/RuntimePars")
grp.attrs["PeriodicBoundariesOn"] = 1

#Units
grp = file.create_group("/Units")
grp.attrs["Unit length in cgs (U_L)"] = 1.
grp.attrs["Unit mass in cgs (U_M)"] = 1.
grp.attrs["Unit time in cgs (U_t)"] = 1.
grp.attrs["Unit current in cgs (U_I)"] = 1.
grp.attrs["Unit temperature in cgs (U_T)"] = 1.

#Particle group
grp = file.create_group("/PartType0")
grp.create_dataset('Coordinates', data=coords, dtype='d')
grp.create_dataset('Velocities', data=v, dtype='f')
grp.create_dataset('Masses', data=m, dtype='f')
grp.create_dataset('SmoothingLength', data=h, dtype='f')
grp.create_dataset('InternalEnergy', data=u, dtype='f')
grp.create_dataset('ParticleIDs', data=ids, dtype='L')

file.close()