knudsen_number#
from particula.util import knudsen_number
help(knudsen_number)
Help on module particula.util.knudsen_number in particula.util:
NAME
particula.util.knudsen_number - calculating Knudsen number
DESCRIPTION
TODO:
add a sanity check for mixing radius shapes and temperature shapes
for example, someone may want to calculate knu for [1e-9, 2e-9, 3e-9]
but only at two different temperatures [290, 300].
A solution is to broadcast into a new shape, e.g. (3, 2) with the
leading dim being the radius; or we could simply ban this entirely.
-- implementing tranpose for now.
FUNCTIONS
calculate_knudsen_number(mean_free_path: Union[float, numpy.ndarray[Any, numpy.dtype[numpy.float64]]], particle_radius: Union[float, numpy.ndarray[Any, numpy.dtype[numpy.float64]]]) -> Union[float, numpy.ndarray[Any, numpy.dtype[numpy.float64]]]
Calculate the Knudsen number using the mean free path of the gas and the
radius of the particle. The Knudsen number is a dimensionless number that
indicates the regime of gas flow relative to the size of particles.
Args:
-----
- mean_free_path (Union[float, NDArray[np.float_]]): The mean free path of
the gas molecules [meters (m)].
- particle_radius (Union[float, NDArray[np.float_]]): The radius of the
particle [meters (m)].
Returns:
--------
- Union[float, NDArray[np.float_]]: The Knudsen number, which is the
ratio of the mean free path to the particle radius.
References:
-----------
- For more information at https://en.wikipedia.org/wiki/Knudsen_number
knu(radius=None, mfp=None, **kwargs)
Returns particle's Knudsen number.
The Knudsen number reflects the relative length scales of
the particle and the suspending fluid (air, water, etc.).
This is calculated by the mean free path of the medium
divided by the particle radius.
The Knudsen number is a measure of continuum effects and
deviation thereof. For larger particles, the Knudsen number
goes towards 0. For smaller particles, the Knudsen number
goes towards infinity.
Examples:
```
>>> from particula import u
>>> from particula.util.knudsen_number import knu
>>> # with radius 1e-9 m
>>> knu(radius=1e-9)
<Quantity(66.4798498, 'dimensionless')>
>>> # with radius 1e-9 m and mfp 60 nm
>>> knu(radius=1e-9*u.m, mfp=60*u.nm).m
60.00000000000001
>>> calculating via mfp(**kwargs)
>>> knu(
... radius=1e-9*u.m,
... temperature=300,
... pressure=1e5,
... molecular_weight=0.03,
... )
<Quantity(66.7097062, 'dimensionless')>
```
Args:
radius (float) [m]
mfp (float) [m] (default: util)
Returns:
(float) [dimensionless]
Notes:
mfp can be calculated using mfp(**kwargs);
refer to particula.util.mean_free_path.mfp for more info.
DATA
NDArray = numpy.ndarray[typing.Any, numpy.dtype[+_ScalarType_co]]
Union = typing.Union
Union type; Union[X, Y] means either X or Y.
On Python 3.10 and higher, the | operator
can also be used to denote unions;
X | Y means the same thing to the type checker as Union[X, Y].
To define a union, use e.g. Union[int, str]. Details:
- The arguments must be types and there must be at least one.
- None as an argument is a special case and is replaced by
type(None).
- Unions of unions are flattened, e.g.::
assert Union[Union[int, str], float] == Union[int, str, float]
- Unions of a single argument vanish, e.g.::
assert Union[int] == int # The constructor actually returns int
- Redundant arguments are skipped, e.g.::
assert Union[int, str, int] == Union[int, str]
- When comparing unions, the argument order is ignored, e.g.::
assert Union[int, str] == Union[str, int]
- You cannot subclass or instantiate a union.
- You can use Optional[X] as a shorthand for Union[X, None].
FILE
/opt/hostedtoolcache/Python/3.11.9/x64/lib/python3.11/site-packages/particula/util/knudsen_number.py
import inspect
print(inspect.getsource(knudsen_number))
""" calculating Knudsen number
TODO:
add a sanity check for mixing radius shapes and temperature shapes
for example, someone may want to calculate knu for [1e-9, 2e-9, 3e-9]
but only at two different temperatures [290, 300].
A solution is to broadcast into a new shape, e.g. (3, 2) with the
leading dim being the radius; or we could simply ban this entirely.
-- implementing tranpose for now.
"""
from typing import Union
from numpy.typing import NDArray
import numpy as np
from particula.util.input_handling import in_length, in_radius
from particula.util.mean_free_path import mfp as mfp_func
def knu(
radius=None,
mfp=None,
**kwargs
):
""" Returns particle's Knudsen number.
The Knudsen number reflects the relative length scales of
the particle and the suspending fluid (air, water, etc.).
This is calculated by the mean free path of the medium
divided by the particle radius.
The Knudsen number is a measure of continuum effects and
deviation thereof. For larger particles, the Knudsen number
goes towards 0. For smaller particles, the Knudsen number
goes towards infinity.
Examples:
```
>>> from particula import u
>>> from particula.util.knudsen_number import knu
>>> # with radius 1e-9 m
>>> knu(radius=1e-9)
<Quantity(66.4798498, 'dimensionless')>
>>> # with radius 1e-9 m and mfp 60 nm
>>> knu(radius=1e-9*u.m, mfp=60*u.nm).m
60.00000000000001
>>> calculating via mfp(**kwargs)
>>> knu(
... radius=1e-9*u.m,
... temperature=300,
... pressure=1e5,
... molecular_weight=0.03,
... )
<Quantity(66.7097062, 'dimensionless')>
```
Args:
radius (float) [m]
mfp (float) [m] (default: util)
Returns:
(float) [dimensionless]
Notes:
mfp can be calculated using mfp(**kwargs);
refer to particula.util.mean_free_path.mfp for more info.
"""
mfp_val = mfp_func(**kwargs) if mfp is None else in_length(mfp)
radius = in_radius(radius)
return np.transpose([mfp_val.m]) * mfp_val.u / radius
def calculate_knudsen_number(
mean_free_path: Union[float, NDArray[np.float_]],
particle_radius: Union[float, NDArray[np.float_]]
) -> Union[float, NDArray[np.float_]]:
"""
Calculate the Knudsen number using the mean free path of the gas and the
radius of the particle. The Knudsen number is a dimensionless number that
indicates the regime of gas flow relative to the size of particles.
Args:
-----
- mean_free_path (Union[float, NDArray[np.float_]]): The mean free path of
the gas molecules [meters (m)].
- particle_radius (Union[float, NDArray[np.float_]]): The radius of the
particle [meters (m)].
Returns:
--------
- Union[float, NDArray[np.float_]]: The Knudsen number, which is the
ratio of the mean free path to the particle radius.
References:
-----------
- For more information at https://en.wikipedia.org/wiki/Knudsen_number
"""
return mean_free_path / particle_radius