Merge pull request #732 from slayoo/master

slayoo · web-flow · commit a76084f5a655 · 2022-01-14T18:11:30.000-06:00
moving terminal velocity and coalescence kernels out of "physics"
diff --git a/PySDM/attributes/chemistry/acidity.py b/PySDM/attributes/chemistry/acidity.py
@@ -2,7 +2,7 @@
 pH calculated by finding equilibrium hydrogen ion concentration
 """
 from PySDM.attributes.impl.intensive_attribute import DerivedAttribute
-from PySDM.physics.aqueous_chemistry.support import AQUEOUS_COMPOUNDS
+from PySDM.dynamics.impl.chemistry_utils import AQUEOUS_COMPOUNDS
 from PySDM.backends.impl_numba.methods.chemistry_methods import _conc
 
 
diff --git a/PySDM/attributes/impl/mapper.py b/PySDM/attributes/impl/mapper.py
@@ -13,7 +13,7 @@
 from PySDM.attributes.chemistry import (
     make_mole_amount_factory, make_concentration_factory, Acidity, HydrogenIonConcentration)
 from PySDM.attributes.physics.critical_supersaturation import CriticalSupersaturation
-from PySDM.physics.aqueous_chemistry.support import AQUEOUS_COMPOUNDS
+from PySDM.dynamics.impl.chemistry_utils import AQUEOUS_COMPOUNDS
 from PySDM.physics.surface_tension import Constant
 
 attributes = {
diff --git a/PySDM/attributes/physics/terminal_velocity.py b/PySDM/attributes/physics/terminal_velocity.py
@@ -2,7 +2,7 @@
 particle terminal velocity (used for collision probability and particle displacement)
 """
 from PySDM.attributes.impl.derived_attribute import DerivedAttribute
-from PySDM.physics.terminal_velocity.gunn_and_kinzer import Interpolation
+from PySDM.dynamics.terminal_velocity import Interpolation
 
 
 class TerminalVelocity(DerivedAttribute):
diff --git a/PySDM/backends/impl_numba/methods/chemistry_methods.py b/PySDM/backends/impl_numba/methods/chemistry_methods.py
@@ -6,7 +6,7 @@
 import numpy as np
 from PySDM.backends.impl_numba import conf
 from PySDM.backends.impl_numba.toms748 import toms748_solve
-from PySDM.physics.aqueous_chemistry.support import HenryConsts, SpecificGravities, \
+from PySDM.dynamics.impl.chemistry_utils import HenryConsts, SpecificGravities, \
     MASS_ACCOMMODATION_COEFFICIENTS, DIFFUSION_CONST, GASEOUS_COMPOUNDS, DISSOCIATION_FACTORS, \
     KineticConsts, EquilibriumConsts, k4
 from PySDM.backends.impl_common.backend_methods import BackendMethods
diff --git a/PySDM/dynamics/__init__.py b/PySDM/dynamics/__init__.py
@@ -1,12 +1,12 @@
 """
 Classes representing physicochemical processes:
-`PySDM.dynamics.coalescence.Coalescence`,
+`PySDM.dynamics.collisions.coalescence.Coalescence`,
 `PySDM.dynamics.condensation.Condensation`, ...
 """
-from .coalescence import Coalescence
-from .condensation import Condensation
-from .displacement import Displacement
-from .eulerian_advection import EulerianAdvection
-from .ambient_thermodynamics import AmbientThermodynamics
-from .aqueous_chemistry import AqueousChemistry
-from .freezing import Freezing
+from PySDM.dynamics.collisions.coalescence import Coalescence
+from PySDM.dynamics.condensation import Condensation
+from PySDM.dynamics.displacement import Displacement
+from PySDM.dynamics.eulerian_advection import EulerianAdvection
+from PySDM.dynamics.ambient_thermodynamics import AmbientThermodynamics
+from PySDM.dynamics.aqueous_chemistry import AqueousChemistry
+from PySDM.dynamics.freezing import Freezing
diff --git a/PySDM/dynamics/aqueous_chemistry.py b/PySDM/dynamics/aqueous_chemistry.py
@@ -3,7 +3,7 @@
 """
 from collections import namedtuple
 import numpy as np
-from PySDM.physics.aqueous_chemistry.support import DIFFUSION_CONST, AQUEOUS_COMPOUNDS, \
+from PySDM.dynamics.impl.chemistry_utils import DIFFUSION_CONST, AQUEOUS_COMPOUNDS, \
     GASEOUS_COMPOUNDS, SpecificGravities, M
 
 
diff --git a/PySDM/dynamics/collisions/__init__.py b/PySDM/dynamics/collisions/__init__.py
@@ -0,0 +1,5 @@
+"""
+collisions-related logic including the `PySDM.dynamics.collisions.coalescence.Coalescence`
+ dynamic and coalescence ``PySDM.dynamics.collisions.kernels`
+"""
+from PySDM.dynamics.collisions.coalescence import Coalescence
diff --git a/PySDM/dynamics/collisions/coalescence.py b/PySDM/dynamics/collisions/coalescence.py
diff --git a/PySDM/dynamics/collisions/kernels/__init__.py b/PySDM/dynamics/collisions/kernels/__init__.py
@@ -1,10 +1,10 @@
 """
 Coalescence kernels including
-[Golovin](https://atmos-cloud-sim-uj.github.io/PySDM/physics/coalescence_kernels/golovin.html),
-[Geometric](https://atmos-cloud-sim-uj.github.io/PySDM/physics/coalescence_kernels/geometric.html)
+[Golovin](https://atmos-cloud-sim-uj.github.io/PySDM/physics/collisions/kernels/golovin.html),
+[Geometric](https://atmos-cloud-sim-uj.github.io/PySDM/physics/collisions/kernels/geometric.html)
 and other...
 """
-from .golovin import Golovin
 from .geometric import Geometric
-from .hydrodynamic import Hydrodynamic
+from  .golovin import Golovin
 from .electric import Electric
+from .hydrodynamic import Hydrodynamic
diff --git a/PySDM/dynamics/collisions/kernels/electric.py b/PySDM/dynamics/collisions/kernels/electric.py
@@ -2,7 +2,7 @@
 kernel modelling influence of electric field of 3000V/cm
  as in [Berry 1967](https://doi.org/10.1175/1520-0469(1967)024%3C0688:CDGBC%3E2.0.CO;2)
 """
-from PySDM.physics.coalescence_kernels.impl.parameterized import Parameterized
+from PySDM.dynamics.collisions.kernels.impl.parameterized import Parameterized
 
 
 class Electric(Parameterized):
diff --git a/PySDM/dynamics/collisions/kernels/geometric.py b/PySDM/dynamics/collisions/kernels/geometric.py
@@ -2,7 +2,7 @@
 basic geometric kernel
 """
 from PySDM.physics import constants as const
-from PySDM.physics.coalescence_kernels.impl.gravitational import Gravitational
+from PySDM.dynamics.collisions.kernels.impl.gravitational import Gravitational
 
 
 class Geometric(Gravitational):
diff --git a/PySDM/dynamics/collisions/kernels/golovin.py b/PySDM/dynamics/collisions/kernels/golovin.py
diff --git a/PySDM/dynamics/collisions/kernels/hydrodynamic.py b/PySDM/dynamics/collisions/kernels/hydrodynamic.py
@@ -3,7 +3,7 @@
  [Berry 1967](https://doi.org/10.1175/1520-0469(1967)024%3C0688:CDGBC%3E2.0.CO;2) parameterization
 """
 
-from PySDM.physics.coalescence_kernels.impl.parameterized import Parameterized
+from PySDM.dynamics.collisions.kernels.impl.parameterized import Parameterized
 
 
 class Hydrodynamic(Parameterized):
diff --git a/PySDM/dynamics/collisions/kernels/impl/__init__.py b/PySDM/dynamics/collisions/kernels/impl/__init__.py
diff --git a/PySDM/dynamics/collisions/kernels/impl/gravitational.py b/PySDM/dynamics/collisions/kernels/impl/gravitational.py
diff --git a/PySDM/dynamics/collisions/kernels/impl/parameterized.py b/PySDM/dynamics/collisions/kernels/impl/parameterized.py
diff --git a/PySDM/dynamics/impl/chemistry_utils.py b/PySDM/dynamics/impl/chemistry_utils.py
diff --git a/PySDM/dynamics/terminal_velocity/__init__.py b/PySDM/dynamics/terminal_velocity/__init__.py
@@ -0,0 +1,5 @@
+"""
+particle terminal velocity formulae
+"""
+from PySDM.dynamics.terminal_velocity.gunn_and_kinzer import Interpolation
+from PySDM.dynamics.terminal_velocity.rogers_and_yau import RogersYau
diff --git a/PySDM/dynamics/terminal_velocity/gunn_and_kinzer.py b/PySDM/dynamics/terminal_velocity/gunn_and_kinzer.py
diff --git a/PySDM/dynamics/terminal_velocity/rogers_and_yau.py b/PySDM/dynamics/terminal_velocity/rogers_and_yau.py
diff --git a/PySDM/physics/__init__.py b/PySDM/physics/__init__.py
@@ -1,5 +1,7 @@
 """
-Physical `PySDM.physics.constants` and formulae
+Physical `PySDM.physics.constants` and simple formulae (essentially one-liners)
+  that can be automatically either njit-ted or translated to C (in contrast to
+  more complex code that resides in backends)
 """
 from . import (condensation_coordinate, latent_heat, saturation_vapour_pressure,
     hygroscopicity, drop_growth, surface_tension, diffusion_kinetics, diffusion_thermics,
diff --git a/PySDM/physics/aqueous_chemistry/__init__.py b/PySDM/physics/aqueous_chemistry/__init__.py
diff --git a/PySDM/physics/constants_defaults.py b/PySDM/physics/constants_defaults.py
@@ -15,6 +15,8 @@
 Mv = Substance.from_formula('H2O').mass * si.gram / si.mole
 
 R_str = sci.R * si.joule / si.kelvin / si.mole
+N_A = sci.N_A / si.mole
+
 eps = Mv / Md
 Rd = R_str / Md
 Rv = R_str / Mv
diff --git a/PySDM/physics/surface_tension/compressed_film_ruehl.py b/PySDM/physics/surface_tension/compressed_film_ruehl.py
@@ -25,7 +25,6 @@ def __init__(self, const):
 
     @staticmethod
     def sigma(const, T, v_wet, v_dry, f_org):
-        from scipy import constants as sci # pylint: disable=import-outside-toplevel
         from scipy import optimize # pylint: disable=import-outside-toplevel
 
         # wet radius (m)
@@ -37,10 +36,10 @@ def sigma(const, T, v_wet, v_dry, f_org):
 
         # A is the area one molecule of organic occupies at the droplet surface
         # A_iso = A*f_surf (m^2)
-        A_iso = (4 * const.PI * r_wet**2) / (f_org * v_dry * sci.N_A / const.RUEHL_nu_org)
+        A_iso = (4 * const.PI * r_wet**2) / (f_org * v_dry * const.N_A / const.RUEHL_nu_org)
 
         # solve implicitly for fraction of organic at surface
-        c = (const.RUEHL_m_sigma * sci.N_A) / (2 * sci.R * T)
+        c = (const.RUEHL_m_sigma * const.N_A) / (2 * const.R_str * T)
         f = lambda f_surf: Cb_iso*(1-f_surf)/const.RUEHL_C0 - np.exp(
             c * (const.RUEHL_A0**2 - (A_iso/f_surf)**2)
         )
diff --git a/PySDM/physics/surface_tension/szyszkowski_langmuir.py b/PySDM/physics/surface_tension/szyszkowski_langmuir.py
@@ -23,8 +23,6 @@ def __init__(self, const):
 
     @staticmethod
     def sigma(const, T, v_wet, v_dry, f_org):
-        from scipy import constants as sci # pylint: disable=import-outside-toplevel
-
         r_wet = ((3 * v_wet) / (4 * np.pi))**(1/3) # m - wet radius
 
         # C_bulk is the concentration of the organic in the bulk phase
@@ -33,7 +31,7 @@ def sigma(const, T, v_wet, v_dry, f_org):
 
         # A is the area that one molecule of organic occupies at the droplet surface
         # A_iso = A*f_surf (m^2)
-        A_iso = (4 * np.pi * r_wet**2) / (f_org * v_dry * sci.N_A / const.RUEHL_nu_org)
+        A_iso = (4 * np.pi * r_wet**2) / (f_org * v_dry * const.N_A / const.RUEHL_nu_org)
 
         # fraction of organic at surface
         # quadratic formula, solve equation of state analytically
@@ -43,7 +41,7 @@ def sigma(const, T, v_wet, v_dry, f_org):
         f_surf = (-b + np.sqrt(b**2 - 4*a*c))/(2*a)
 
         # calculate surface tension
-        sgm = const.sgm_w - ((sci.R*T)/(const.RUEHL_A0*sci.N_A)) * np.log(
+        sgm = const.sgm_w - ((const.R_str*T)/(const.RUEHL_A0*const.N_A)) * np.log(
             1 + Cb_iso*(1-f_surf)/const.RUEHL_C0
         )
         sgm = np.minimum(np.maximum(sgm, const.RUEHL_sgm_min), const.sgm_w)
diff --git a/PySDM/physics/terminal_velocity/__init__.py b/PySDM/physics/terminal_velocity/__init__.py
diff --git a/PySDM/products/aqueous_chemistry/aqueous_mass_spectrum.py b/PySDM/products/aqueous_chemistry/aqueous_mass_spectrum.py
@@ -6,7 +6,7 @@
 from chempy import Substance
 from PySDM.physics.constants import si
 from PySDM.products.impl.spectrum_moment_product import SpectrumMomentProduct
-from PySDM.physics.aqueous_chemistry.support import AQUEOUS_COMPOUNDS
+from PySDM.dynamics.impl.chemistry_utils import AQUEOUS_COMPOUNDS
 
 
 class AqueousMassSpectrum(SpectrumMomentProduct):
diff --git a/PySDM/products/aqueous_chemistry/gaseous_mole_fraction.py b/PySDM/products/aqueous_chemistry/gaseous_mole_fraction.py
@@ -2,7 +2,7 @@
 mole fractions of gaseous compounds relevant for aqueous chemistry
 """
 from PySDM.products.impl.product import Product
-from PySDM.physics.aqueous_chemistry.support import GASEOUS_COMPOUNDS
+from PySDM.dynamics.impl.chemistry_utils import GASEOUS_COMPOUNDS
 
 
 class GaseousMoleFraction(Product):
diff --git a/PySDM/products/coalescence/__init__.py b/PySDM/products/coalescence/__init__.py
@@ -1,5 +1,5 @@
 """
-products pertinent to the `PySDM.dynamics.coalescence.Coalescence` dynamic
+products pertinent to the `PySDM.dynamics.collisions.coalescence.Coalescence` dynamic
 """
 from .coalescence_timestep_mean import CoalescenceTimestepMean
 from .coalescence_timestep_min import CoalescenceTimestepMin
diff --git a/PySDM/products/coalescence/coalescence_timestep_mean.py b/PySDM/products/coalescence/coalescence_timestep_mean.py
@@ -1,6 +1,6 @@
 """
 Average coalescence timestep length used when adaptive timestepping is enabled in the
- `PySDM.dynamics.coalescence.Coalescence` dynamic (fetching a value reset the counter)
+ `PySDM.dynamics.collisions.coalescence.Coalescence` dynamic (fetching a value reset the counter)
 """
 import numpy as np
 import numba
diff --git a/PySDM/products/coalescence/coalescence_timestep_min.py b/PySDM/products/coalescence/coalescence_timestep_min.py
@@ -1,6 +1,6 @@
 """
 Minimal coalescence timestep used when adaptive timestepping is enabled in the
- `PySDM.dynamics.coalescence.Coalescence` dynamic (fetching a value reset the counter)
+ `PySDM.dynamics.collisions.coalescence.Coalescence` dynamic (fetching a value reset the counter)
 """
 from PySDM.products.impl.product import Product
 
diff --git a/README.md b/README.md
@@ -167,7 +167,7 @@ Instantiation of the [``Particulator``](https://atmos-cloud-sim-uj.github.io/PyS
 Builder = pyimport("PySDM").Builder
 Box = pyimport("PySDM.environments").Box
 Coalescence = pyimport("PySDM.dynamics").Coalescence
-Golovin = pyimport("PySDM.physics.coalescence_kernels").Golovin
+Golovin = pyimport("PySDM.dynamics.collisions.kernels").Golovin
 CPU = pyimport("PySDM.backends").CPU
 ParticleVolumeVersusRadiusLogarithmSpectrum = pyimport("PySDM.products").ParticleVolumeVersusRadiusLogarithmSpectrum
 
@@ -187,7 +187,7 @@ particulator = builder.build(attributes, products)
 Builder = py.importlib.import_module('PySDM').Builder;
 Box = py.importlib.import_module('PySDM.environments').Box;
 Coalescence = py.importlib.import_module('PySDM.dynamics').Coalescence;
-Golovin = py.importlib.import_module('PySDM.physics.coalescence_kernels').Golovin;
+Golovin = py.importlib.import_module('PySDM.dynamics.collisions.kernels').Golovin;
 CPU = py.importlib.import_module('PySDM.backends').CPU;
 ParticleVolumeVersusRadiusLogarithmSpectrum = py.importlib.import_module('PySDM.products').ParticleVolumeVersusRadiusLogarithmSpectrum;
 
@@ -211,7 +211,7 @@ import numpy as np
 from PySDM import Builder
 from PySDM.environments import Box
 from PySDM.dynamics import Coalescence
-from PySDM.physics.coalescence_kernels import Golovin
+from PySDM.dynamics.collisions.kernels import Golovin
 from PySDM.backends import CPU
 from PySDM.products import ParticleVolumeVersusRadiusLogarithmSpectrum
 
diff --git a/paper/paper.md b/paper/paper.md
@@ -158,7 +158,7 @@ import numpy as np
 from PySDM.builder import Builder
 from PySDM.environments import Box
 from PySDM.dynamics import Coalescence
-from PySDM.physics.coalescence_kernels import Golovin
+from PySDM.dynamics.collisions.kernels import Golovin
 from PySDM.backends import CPU
 from PySDM.products import ParticleVolumeVersusRadiusLogarithmSpectrum
 
diff --git a/test-time-requirements.txt b/test-time-requirements.txt
@@ -4,4 +4,4 @@ ghapi
 pytest
 
 # note: if cloning both PySDM and PySDM examples, consider "pip install -e"
-PySDM-examples @ git+git://github.com/atmos-cloud-sim-uj/PySDM-examples@c024558#egg=PySDM-examples
+PySDM-examples @ git+git://github.com/slayoo/PySDM-examples@fb4df0f#egg=PySDM-examples
diff --git a/tests/smoke_tests/berry_1967/test_coalescence.py b/tests/smoke_tests/berry_1967/test_coalescence.py
@@ -8,7 +8,7 @@
 from PySDM.dynamics import Coalescence
 from PySDM.environments import Box
 from PySDM.initialisation.sampling.spectral_sampling import ConstantMultiplicity
-from PySDM.physics.coalescence_kernels import Golovin, Geometric, Electric, Hydrodynamic
+from PySDM.dynamics.collisions.kernels import Golovin, Geometric, Electric, Hydrodynamic
 from ...backends_fixture import backend_class
 
 assert hasattr(backend_class, '_pytestfixturefunction')
diff --git a/tests/smoke_tests/kreidenweis_et_al_2003/test_fig_1.py b/tests/smoke_tests/kreidenweis_et_al_2003/test_fig_1.py
@@ -3,7 +3,7 @@
 import numpy as np
 import pytest
 from PySDM_examples.Kreidenweis_et_al_2003 import Settings, Simulation
-from PySDM.physics.aqueous_chemistry.support import GASEOUS_COMPOUNDS
+from PySDM.dynamics.impl.chemistry_utils import GASEOUS_COMPOUNDS
 from PySDM.physics import si
 
 
diff --git a/tests/smoke_tests/kreidenweis_et_al_2003/test_ionic_strength.py b/tests/smoke_tests/kreidenweis_et_al_2003/test_ionic_strength.py
@@ -6,7 +6,7 @@
 from PySDM.backends.impl_numba.methods.chemistry_methods import calc_ionic_strength, _K, _conc
 from PySDM.physics.constants import K_H2O
 from PySDM import Formulae
-from PySDM.physics.aqueous_chemistry.support import EquilibriumConsts
+from PySDM.dynamics.impl.chemistry_utils import EquilibriumConsts
 
 
 @pytest.mark.parametrize("nt", (0, 1, 2, 3))
diff --git a/tests/smoke_tests/kreidenweis_et_al_2003/test_table_3.py b/tests/smoke_tests/kreidenweis_et_al_2003/test_table_3.py
@@ -4,7 +4,7 @@
 from PySDM_examples.Kreidenweis_et_al_2003 import Settings, Simulation
 from PySDM.physics import si
 from PySDM.physics.constants import convert_to, PPB
-from PySDM.physics.aqueous_chemistry.support import AQUEOUS_COMPOUNDS, SpecificGravities
+from PySDM.dynamics.impl.chemistry_utils import AQUEOUS_COMPOUNDS, SpecificGravities
 
 
 class TestTable3:
diff --git a/tests/smoke_tests/shima_et_al_2009/test_coalescence.py b/tests/smoke_tests/shima_et_al_2009/test_coalescence.py
@@ -5,7 +5,7 @@
 from PySDM.backends import ThrustRTC
 from PySDM.builder import Builder
 from PySDM.dynamics import Coalescence
-from PySDM.physics.coalescence_kernels import Golovin
+from PySDM.dynamics.collisions.kernels import Golovin
 from PySDM.environments import Box
 from PySDM.initialisation.spectra import Exponential
 from PySDM.initialisation.sampling.spectral_sampling import ConstantMultiplicity
diff --git a/tests/unit_tests/attributes/test_acidity.py b/tests/unit_tests/attributes/test_acidity.py
@@ -5,7 +5,7 @@
 from chempy import Equilibrium
 from chempy.equilibria import EqSystem
 from chempy.chemistry import Species
-from PySDM.physics.aqueous_chemistry.support import M, EquilibriumConsts
+from PySDM.dynamics.impl.chemistry_utils import M, EquilibriumConsts
 from PySDM.physics.constants import K_H2O
 from PySDM.formulae import Formulae
 from PySDM.backends.impl_numba.methods.chemistry_methods import ChemistryMethods, _K, _conc
diff --git a/tests/unit_tests/attributes/test_terminal_velocity.py b/tests/unit_tests/attributes/test_terminal_velocity.py
@@ -2,8 +2,8 @@
 import matplotlib.pyplot as plt
 import numpy as np
 from PySDM.physics import constants as const
-from PySDM.physics.terminal_velocity.gunn_and_kinzer import Interpolation
-from PySDM.physics.terminal_velocity.rogers_and_yau import RogersYau
+from PySDM.dynamics.terminal_velocity import Interpolation
+from PySDM.dynamics.terminal_velocity import RogersYau
 from tests.backends_fixture import backend_class
 from tests.unit_tests.dummy_particulator import DummyParticulator
 
diff --git a/tests/unit_tests/backends/test_oxidation.py b/tests/unit_tests/backends/test_oxidation.py
@@ -5,7 +5,7 @@
 from PySDM.backends.impl_numba.methods.chemistry_methods import ChemistryMethods
 from PySDM.backends.impl_numba.storage import Storage
 from PySDM.physics import si
-from PySDM.physics.aqueous_chemistry.support import KineticConsts, EquilibriumConsts, \
+from PySDM.dynamics.impl.chemistry_utils import KineticConsts, EquilibriumConsts, \
     DISSOCIATION_FACTORS, k4
 from PySDM.physics.constants import PI_4_3
 from PySDM.physics.constants_defaults import T_STP
diff --git a/tests/unit_tests/dynamics/coalescence/__parametrisation__.py b/tests/unit_tests/dynamics/coalescence/__parametrisation__.py
@@ -2,7 +2,7 @@
 import numpy as np
 import pytest
 
-from PySDM.dynamics.coalescence import Coalescence, DEFAULTS
+from PySDM.dynamics.collisions.coalescence import Coalescence, DEFAULTS
 from PySDM.environments import Box
 from ....unit_tests.dummy_particulator import DummyParticulator
 
diff --git a/tests/unit_tests/dynamics/coalescence/test_kernels.py b/tests/unit_tests/dynamics/coalescence/test_kernels.py
@@ -2,7 +2,7 @@
 import numpy as np
 import pytest
 from PySDM.formulae import Formulae
-from PySDM.physics.coalescence_kernels import Golovin
+from PySDM.dynamics.collisions.kernels import Golovin
 
 
 class TestGolovin:
diff --git a/tests/unit_tests/dynamics/coalescence/test_sdm_multi_cell.py b/tests/unit_tests/dynamics/coalescence/test_sdm_multi_cell.py
@@ -5,7 +5,7 @@
 from PySDM.environments import Box
 from PySDM.initialisation.sampling.spatial_sampling import Pseudorandom
 from PySDM.impl.mesh import Mesh
-from PySDM.dynamics.coalescence import DEFAULTS
+from PySDM.dynamics.collisions.coalescence import DEFAULTS
 from ....backends_fixture import backend_class
 from .__parametrisation__ import get_dummy_particulator_and_coalescence
 
