############################################################################### # This file is part of SWIFT. # Copyright (c) 2025 Thomas Sandnes (thomas.d.sandnes@durham.ac.uk) # 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 . # ############################################################################## import h5py import numpy as np # Generates a swift IC file for the Kelvin-Helmholtz test in a periodic box # Parameters N_l = 128 # Particles along one edge in the low-density region N_depth = 18 # Particles in z direction in low-density region gamma = 5.0 / 3.0 # Gas adiabatic index P1 = 2.5 # Central region pressure P2 = 2.5 # Outskirts pressure rho1 = 2 # Central region density rho2 = 1 # Outskirts density v1 = 0.5 # Central region velocity v2 = -0.5 # Outskirts velocity boxsize_l = 1 # size of simulation box in x and y dimension boxsize_depth = boxsize_l * N_depth / N_l # size of simulation box in z dimension fileOutputName = "kelvin_helmholtz.hdf5" # Parameters for smoothing of interfaces vm = (v2 - v1) / 2 rhom = (rho2 - rho1) / 2 delta = 0.025 # --------------------------------------------------- numPart = N_l * N_l * N_depth # Now construct two lattices of particles in the two regions A2_coords = np.empty((numPart, 3)) A2_vel = np.zeros((numPart, 3)) A1_mat = np.zeros(numPart) A1_m = np.empty(numPart) A1_rho = np.empty(numPart) A1_u = np.empty(numPart) A1_h = np.ones(numPart) * boxsize_l / N_l A1_ids = np.linspace(1, numPart, numPart) # Set up particles for i in range(N_depth): for j in range(N_l): for k in range(N_l): index = i * N_l ** 2 + j * N_l + k x = (j / float(N_l) + 1.0 / (2.0 * N_l)) * boxsize_l y = (k / float(N_l) + 1.0 / (2.0 * N_l)) * boxsize_l z = (i / float(N_depth) + 1.0 / (2.0 * N_depth)) * boxsize_depth A2_coords[index, 0] = x A2_coords[index, 1] = y A2_coords[index, 2] = z if 0.0 <= y <= 0.25: A1_rho[index] = rho2 - rhom * np.exp((y - 0.25) / delta) A2_vel[index, 0] = v2 - vm * np.exp((y - 0.25) / delta) A1_m[index] = A1_rho[index] / N_l ** 3 A1_u[index] = P2 / (A1_rho[index] * (gamma - 1.0)) elif 0.25 <= y <= 0.5: A1_rho[index] = rho1 + rhom * np.exp((0.25 - y) / delta) A2_vel[index, 0] = v1 + vm * np.exp((0.25 - y) / delta) A1_m[index] = A1_rho[index] / N_l ** 3 A1_u[index] = P1 / (A1_rho[index] * (gamma - 1.0)) elif 0.5 <= y <= 0.75: A1_rho[index] = rho1 + rhom * np.exp((y - 0.75) / delta) A2_vel[index, 0] = v1 + vm * np.exp((y - 0.75) / delta) A1_m[index] = A1_rho[index] / N_l ** 3 A1_u[index] = P1 / (A1_rho[index] * (gamma - 1.0)) elif 0.75 <= y <= 1: A1_rho[index] = rho2 - rhom * np.exp((0.75 - y) / delta) A2_vel[index, 0] = v2 - vm * np.exp((0.75 - y) / delta) A1_m[index] = A1_rho[index] / N_l ** 3 A1_u[index] = P2 / (A1_rho[index] * (gamma - 1.0)) # Finally add the velocity perturbation vel_perturb_factor = 0.01 * (v1 - v2) A2_vel[:, 1] = vel_perturb_factor * np.sin( 2 * np.pi * A2_coords[:, 0] / (0.5 * boxsize_l) ) # Write ICs to file with h5py.File(fileOutputName, "w") as f: # Header grp = f.create_group("/Header") grp.attrs["BoxSize"] = [boxsize_l, boxsize_l, boxsize_depth] 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["NumFileOutputsPerSnapshot"] = 1 grp.attrs["MassTable"] = [0.0, 0.0, 0.0, 0.0, 0.0, 0.0] grp.attrs["Flag_Entropy_ICs"] = [0, 0, 0, 0, 0, 0] grp.attrs["Dimension"] = 3 # Units grp = f.create_group("/Units") grp.attrs["Unit length in cgs (U_L)"] = 1.0 grp.attrs["Unit mass in cgs (U_M)"] = 1.0 grp.attrs["Unit time in cgs (U_t)"] = 1.0 grp.attrs["Unit current in cgs (U_I)"] = 1.0 grp.attrs["Unit temperature in cgs (U_T)"] = 1.0 # Particle group grp = f.create_group("/PartType0") ds = grp.create_dataset("Coordinates", (numPart, 3), "d") ds[()] = A2_coords ds = grp.create_dataset("Velocities", (numPart, 3), "f") ds[()] = A2_vel ds = grp.create_dataset("Masses", (numPart, 1), "f") ds[()] = A1_m.reshape((numPart, 1)) ds = grp.create_dataset("Density", (numPart, 1), "f") ds[()] = A1_rho.reshape((numPart, 1)) ds = grp.create_dataset("SmoothingLength", (numPart, 1), "f") ds[()] = A1_h.reshape((numPart, 1)) ds = grp.create_dataset("InternalEnergy", (numPart, 1), "f") ds[()] = A1_u.reshape((numPart, 1)) ds = grp.create_dataset("ParticleIDs", (numPart, 1), "L") ds[()] = A1_ids.reshape((numPart, 1)) ds = grp.create_dataset("MaterialIDs", (numPart, 1), "i") ds[()] = A1_mat.reshape((numPart, 1))