PICMI_inputs_2d.py

#!/usr/bin/env python3
import argparse
import sys

import numpy as np

from pywarpx import callbacks, libwarpx, particle_containers, picmi

# Create the parser and add the argument
parser = argparse.ArgumentParser()
parser.add_argument(
    '-u', '--unique', action='store_true',
    help="Whether injected particles should be treated as unique"
)

# Parse the input
args, left = parser.parse_known_args()
sys.argv = sys.argv[:1] + left

##########################
# numerics parameters
##########################

dt = 7.5e-10

# --- Nb time steps

max_steps = 10

# --- grid

nx = 64
ny = 64

xmin = 0
xmax = 0.03
ymin = 0
ymax = 0.03

##########################
# numerics components
##########################

grid = picmi.Cartesian2DGrid(
    number_of_cells = [nx, ny],
    lower_bound = [xmin, ymin],
    upper_bound = [xmax, ymax],
    lower_boundary_conditions = ['dirichlet', 'periodic'],
    upper_boundary_conditions = ['dirichlet', 'periodic'],
    lower_boundary_conditions_particles = ['absorbing', 'periodic'],
    upper_boundary_conditions_particles = ['absorbing', 'periodic'],
    moving_window_velocity = None,
    warpx_max_grid_size = 32
)

solver = picmi.ElectrostaticSolver(
    grid=grid, method='Multigrid', required_precision=1e-6,
    warpx_self_fields_verbosity=0
)

##########################
# physics components
##########################

electrons = picmi.Species(
    particle_type='electron', name='electrons'
)

##########################
# diagnostics
##########################

particle_diag = picmi.ParticleDiagnostic(
    name = 'diag1',
    period = 10,
    write_dir = '.',
    warpx_file_prefix = f"Python_particle_attr_access_{'unique_' if args.unique else ''}plt"
)
field_diag = picmi.FieldDiagnostic(
    name = 'diag1',
    grid = grid,
    period = 10,
    data_list = ['phi'],
    write_dir = '.',
    warpx_file_prefix = f"Python_particle_attr_access_{'unique_' if args.unique else ''}plt"
)

##########################
# simulation setup
##########################

sim = picmi.Simulation(
    solver = solver,
    time_step_size = dt,
    max_steps = max_steps,
    verbose = 1
)

sim.add_species(
    electrons,
    layout = picmi.GriddedLayout(
        n_macroparticle_per_cell=[0, 0], grid=grid
    )
)
sim.add_diagnostic(particle_diag)
sim.add_diagnostic(field_diag)

sim.initialize_inputs()
sim.initialize_warpx()

##########################
# python particle data access
##########################

# set numpy random seed so that the particle properties generated
# below will be reproducible from run to run
np.random.seed(30025025)

elec_wrapper = particle_containers.ParticleContainerWrapper('electrons')
elec_wrapper.add_real_comp('newPid')

my_id = libwarpx.amr.ParallelDescriptor.MyProc()

def add_particles():

    nps = 10 * (my_id + 1)
    x = np.linspace(0.005, 0.025, nps)
    y = np.zeros(nps)
    z = np.linspace(0.005, 0.025, nps)
    ux = np.random.normal(loc=0, scale=1e3, size=nps)
    uy = np.random.normal(loc=0, scale=1e3, size=nps)
    uz = np.random.normal(loc=0, scale=1e3, size=nps)
    w = np.ones(nps) * 2.0
    newPid = 5.0

    elec_wrapper.add_particles(
        x=x, y=y, z=z, ux=ux, uy=uy, uz=uz,
        w=w, newPid=newPid,
        unique_particles=args.unique
    )

callbacks.installbeforestep(add_particles)

##########################
# simulation run
##########################

sim.step(max_steps - 1)

##########################
# check that the new PIDs
# are properly set
##########################

assert (elec_wrapper.nps == 270 / (2 - args.unique))
assert (elec_wrapper.particle_container.get_comp_index('w') == 2)
assert (elec_wrapper.particle_container.get_comp_index('newPid') == 6)

new_pid_vals = elec_wrapper.get_particle_real_arrays('newPid', 0)
for vals in new_pid_vals:
    assert np.allclose(vals, 5)

##########################
# take the final sim step
##########################

sim.step(1)