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Hall kernel #1526

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2473200
Hall kernel
jbarr444 Mar 8, 2025
d81238c
Test for hall effeciencies
jbarr444 Mar 11, 2025
57dadd1
Added docstrings, fixed import path (i think), added numba decorator
jbarr444 Mar 13, 2025
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345 changes: 345 additions & 0 deletions PySDM/dynamics/collisions/collision_kernels/hall.py
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"""
collision kernel from Hall et. al. 1980.
"""

import numpy as np
import numba as nb
from scipy.interpolate import RegularGridInterpolator
from PySDM.dynamics.collisions.collision_kernels.geometric import Geometric


class Hall(Geometric):

def table(self, collector_radius_m, collected_radius_m):

collector_radii_um = np.array(
[300, 200, 150, 100, 70, 60, 50, 40, 30, 20, 10], dtype=float
)
ratio_values = np.array(
[
0.05,
0.10,
0.15,
0.20,
0.25,
0.30,
0.35,
0.40,
0.45,
0.50,
0.55,
0.60,
0.65,
0.70,
0.75,
0.80,
0.85,
0.90,
0.95,
1.00,
],
dtype=float,
)

table_data = np.array(
[
# For collector radius = 300 µm:
[
0.97,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
],
# For collector radius = 200 µm:
[
0.87,
0.96,
0.98,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
],
# For collector radius = 150 µm:
[
0.77,
0.93,
0.97,
0.97,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
],
# For collector radius = 100 µm:
[
0.50,
0.79,
0.91,
0.95,
0.95,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
1.0,
],
# For collector radius = 70 µm:
[
0.20,
0.58,
0.75,
0.84,
0.88,
0.90,
0.92,
0.94,
0.95,
0.95,
0.95,
0.95,
0.95,
0.95,
0.97,
1.0,
1.02,
1.04,
2.3,
4.0,
],
# For collector radius = 60 µm:
[
0.05,
0.43,
0.64,
0.77,
0.84,
0.87,
0.89,
0.90,
0.91,
0.91,
0.91,
0.91,
0.91,
0.92,
0.93,
0.95,
1.0,
1.03,
1.7,
3.0,
],
# For collector radius = 50 µm:
[
0.005,
0.40,
0.60,
0.70,
0.78,
0.83,
0.86,
0.88,
0.90,
0.90,
0.90,
0.90,
0.89,
0.88,
0.88,
0.89,
0.92,
1.01,
1.3,
2.3,
],
# For collector radius = 40 µm:
[
0.001,
0.07,
0.28,
0.50,
0.62,
0.68,
0.74,
0.78,
0.80,
0.80,
0.80,
0.78,
0.77,
0.76,
0.77,
0.77,
0.78,
0.79,
0.95,
1.4,
],
# For collector radius = 30 µm:
[
0.001,
0.002,
0.02,
0.04,
0.085,
0.17,
0.27,
0.40,
0.50,
0.55,
0.58,
0.59,
0.58,
0.54,
0.51,
0.49,
0.47,
0.45,
0.47,
0.52,
],
# For collector radius = 20 µm:
[
0.0001,
0.0001,
0.005,
0.016,
0.022,
0.03,
0.043,
0.052,
0.064,
0.072,
0.079,
0.082,
0.080,
0.076,
0.067,
0.057,
0.048,
0.040,
0.033,
0.027,
],
# For collector radius = 10 µm:
[
0.0001,
0.0001,
0.0001,
0.014,
0.017,
0.019,
0.022,
0.027,
0.030,
0.033,
0.035,
0.037,
0.038,
0.038,
0.037,
0.036,
0.035,
0.032,
0.029,
0.027,
],
],
dtype=float,
)

# Sort collector radii ascending:
idx_sorted = np.argsort(collector_radii_um)
collector_radii_um_sorted = collector_radii_um[idx_sorted]
table_data_sorted = table_data[idx_sorted, :]

interpolator = RegularGridInterpolator(
(collector_radii_um_sorted, ratio_values),
table_data_sorted,
bounds_error=False,
fill_value=None,
)

R_um = collector_radius_m * 1e6
r_um = collected_radius_m * 1e6

ratio = r_um / R_um

if ratio > 1:
ratio = 1 / ratio
R_um, r_um = r_um, R_um

result = interpolator([R_um, ratio])

return float(result)

@nb.njit(parallel=True)
def __call__(self, output, is_first_in_pair):
output.sum(self.particulator.attributes["radius"], is_first_in_pair)
output **= 2
output *= np.pi
self.pair_tmp.distance(
self.particulator.attributes["relative fall velocity"], is_first_in_pair
)
output *= self.pair_tmp
idx = self.particulator.attributes["radius"].idx
for i in nb.prange(len(idx) - 1):
if is_first_in_pair.indicator.data[i]:
temp = float(output[i // 2])
temp *= self.table(
self.particulator.attributes["radius"].data[idx[i]],
self.particulator.attributes["radius"].data[idx[i + 1]],
)
output[i // 2] = temp
14 changes: 14 additions & 0 deletions tests/unit_tests/dynamics/collisions/test_table.py
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"""
Test the table function in the Hall class.
"""

from PySDM.dynamics.collisions.collision_kernels.hall import Hall


def test_table():
hall = Hall()
collector_radius_m = 2e-5
collected_radius_m = 1e-6
result1 = hall.table(collected_radius_m, collector_radius_m)
result2 = hall.table(collector_radius_m, collected_radius_m)
assert result1 == result2 == 1e-4, "Test failed"
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