def set_timestep(vel):
gyperiod = (2*np.pi) / const.gyfreq # Gyroperiod within uniform field (s)
ion_ts = const.orbit_res * gyperiod # Timestep to resolve gyromotion
vel_ts = const.dx / (2 * np.max(vel[0, :])) # Timestep to satisfy CFL condition: Fastest particle doesn't traverse more than half a cell in one time step
DT = min(ion_ts, vel_ts)
max_time = const.max_rev * gyperiod # Total runtime in seconds
max_inc = int(max_time / DT) + 1 # Total number of time steps
if const.plot_res == 0: # Decide plot and data increments (if enabled)
plot_iter = 1
else:
plot_iter = int(const.plot_res*gyperiod / DT)
if const.data_res == 0:
data_iter = 1
else:
data_iter = int(const.data_res*gyperiod / DT)
print 'Timestep: %.4fs, %d iterations total' % (DT, max_inc)
if const.adaptive_subcycling == True:
k_max = np.pi / const.dx
dispfreq = (k_max ** 2) * const.B0 / (const.mu0 * const.ne * const.q) # Dispersion frequency
dt_sc = const.freq_res * 1./dispfreq
subcycles = int(DT / dt_sc + 1)
print 'Number of subcycles required: {}'.format(subcycles)
else:
subcycles = const.subcycles
print 'Number of subcycles set at default: {}'.format(subcycles)
if const.generate_data == 1:
pas.store_run_parameters(DT, data_iter)
return DT, max_inc, data_iter, plot_iter, subcycles
def set_timestep(vel):
gyperiod = (2 *
np.pi) / const.gyfreq # Gyroperiod within uniform field (s)
k_max = np.pi / const.dx
ion_ts = const.orbit_res * gyperiod # Timestep to resolve gyromotion
vel_ts = 0.5 * const.dx / np.max(
vel[0, :]
) # Timestep to satisfy CFL condition: Fastest particle doesn't traverse more than half a cell in one time step
if const.account_for_dispersion == True:
dispfreq = (k_max**2) * (const.B0 / (const.mu0 * const.ne)
) # Dispersion frequency
disp_ts = const.dispersion_allowance * const.freq_res / dispfreq
else:
disp_ts = ion_ts
DT = min(ion_ts, vel_ts, disp_ts)
max_time = const.max_rev * gyperiod # Total runtime in seconds
max_inc = int(max_time / DT) + 1 # Total number of time steps
if const.plot_res == 0: # Decide plot and data increments (if enabled)
plot_iter = 1
else:
plot_iter = int(const.plot_res * gyperiod / DT)
if const.data_res == 0:
data_iter = 1
else:
data_iter = int(const.data_res * gyperiod / DT)
print('Timestep: %.4fs, %d iterations total' % (DT, max_inc))
if const.generate_data == 1:
pas.store_run_parameters(DT, data_iter)
return DT, max_inc, data_iter, plot_iter
import sources_1D as sources
import plot_and_save as pas
import diagnostics as diag
from simulation_parameters_1D import generate_data, generate_plots
if __name__ == '__main__':
start_time = timer()
part = init.initialize_particles()
B, E = init.initialize_magnetic_field()
DT, max_inc, data_dump_iter, plot_dump_iter = aux.set_timestep(part)
if generate_data == 1:
pas.store_run_parameters(DT, data_dump_iter)
print('Loading initial state...\n')
part, dns_int, dns_half, J_plus, J_minus, G, L = sources.init_collect_moments(
part, 0.5 * DT)
qq = 0
while qq < max_inc:
part, qq, DT, max_inc, data_dump_iter, plot_dump_iter, change_flag = aux.check_timestep(
qq, DT, part, B, E, dns_int, max_inc, data_dump_iter,
plot_dump_iter)
if change_flag == 1:
print(
'Timestep halved. Syncing particle velocity/position with DT = {}'
.format(DT))