def conduit_lengths(target,
throat_endpoints='throat.endpoints',
throat_length='throat.length'):
r"""
Calculate conduit lengths. A conduit is defined as half pore + throat
+ half pore.
Parameters
----------
target : OpenPNM Object
The object which this model is associated with. This controls the
length of the calculated array, and also provides access to other
necessary properties.
throat_endpoints : string
Dictionary key of the throat endpoint values.
throat_diameter : string
Dictionary key of the throat length values.
throat_length : string (optional)
Dictionary key of the throat length values. If not given then the
direct distance bewteen the two throat end points is used.
Returns
-------
Dictionary containing conduit lengths, which can be accessed via the dict
keys 'pore1', 'pore2', and 'throat'.
"""
network = target.project.network
throats = network.map_throats(throats=target.Ts, origin=target)
cn = network['throat.conns'][throats]
# Get pore coordinates
C1 = network['pore.coords'][cn[:, 0]]
C2 = network['pore.coords'][cn[:, 1]]
# Get throat endpoints and length
EP1 = network[throat_endpoints + '.head'][throats]
EP2 = network[throat_endpoints + '.tail'][throats]
try:
# Look up throat length if given
Lt = network[throat_length][throats]
except KeyError:
# Calculate throat length otherwise
Lt = _norm(EP1 - EP2, axis=1)
# Calculate conduit lengths
L1 = _norm(C1 - EP1, axis=1)
L2 = _norm(C2 - EP2, axis=1)
return {'pore1': L1, 'throat': Lt, 'pore2': L2}
def piecewise(target,
throat_endpoints='throat.endpoints',
throat_centroid='throat.centroid'):
r"""
Calculate throat length from end points and optionally a centroid
Parameters
----------
target : OpenPNM Object
The object which this model is associated with. This controls the
length of the calculated array, and also provides access to other
necessary properties.
throat_endpoints : string
Dictionary key of the throat endpoint values.
throat_centroid : string
Dictionary key of the throat centroid values, optional.
Returns
-------
Lt : ndarray
Array containing throat lengths for the given geometry.
Notes
-----
(1) By default, the model assumes that the centroids of pores and the
connecting throat in each conduit are colinear.
(2) If `throat_centroid` is passed, the model accounts for the extra
length. This could be useful for Voronoi or extracted networks.
"""
network = target.project.network
throats = network.map_throats(throats=target.Ts, origin=target)
# Get throat endpoints
EP1 = network[throat_endpoints + '.head'][throats]
EP2 = network[throat_endpoints + '.tail'][throats]
# Calculate throat length
Lt = _norm(EP1 - EP2, axis=1)
# Handle the case where pores & throat centroids are not colinear
try:
Ct = network[throat_centroid][throats]
Lt = _norm(Ct - EP1, axis=1) + _norm(Ct - EP2, axis=1)
except KeyError:
pass
return Lt
def discrete_error(X, Y):
"""Compute the absolute and relative l2-norm errors between two snapshot
sets X and Y where Y is an approximation to X,
Abs_Err_j = ||X_j - Y_j||_2,
Rel_Err_j = ||X_j - Y_j||_2 / ||X_j||_2 = Abs_Err_j / ||X_j||_2.
Parameters
----------
X : (n,k) or (n,) ndarray
The "true" data. Each column is one snapshot, i.e., X[:,j] is the data
at some time t[j]. If one-dimensional, all of X is a single snapshot.
Y : (n,k) or (n,) ndarray
An approximation to X, i.e., Y[:,j] approximates X[:,j] and corresponds
to some time t[j]. If one-dimensional, all of Y is a single snapshot
approximation.
Returns
-------
abs_err : (k,) ndarray or float
The absolute error of each pair of snapshots X[:,j] and Y[:,j]. If X
and Y are one-dimensional, X and Y are treated as single snapshots, so
the error is a float.
rel_err : (k,) ndarray or float
The relative error of each pair of snapshots X[:,j] and Y[:,j]. If X
and Y are one-dimensional, X and Y are treated as single snapshots, so
the error is a float. Note that this error may be deceptively large
when the norm of a true snapshot, ||X_j|| is small.
"""
# Check dimensions.
if X.shape != Y.shape:
raise ValueError("truth X and approximation Y not aligned")
if X.ndim not in (1, 2):
raise ValueError("X and Y must be one- or two-dimensional")
# Compute the error.
norm_of_data = _norm(X, axis=0)
absolute_error = _norm(X - Y, axis=0)
return absolute_error, absolute_error / norm_of_data
def ctc(target, pore_diameter='pore.diameter'):
r"""
Calculate throat length assuming point-like pores, i.e. center-to-center
distance between pores. Also, this models assumes that pores and throat
centroids are colinear.
Parameters
----------
target : OpenPNM Object
The object which this model is associated with. This controls the
length of the calculated array, and also provides access to other
necessary properties.
pore_diameter : string
Dictionary key of the pore diameter values
"""
network = target.project.network
throats = network.map_throats(throats=target.Ts, origin=target)
cn = network['throat.conns'][throats]
C1 = network['pore.coords'][cn[:, 0]]
C2 = network['pore.coords'][cn[:, 1]]
return _norm(C1 - C2, axis=1)
def norm(x, p=2):
if not isfinite(x).all():
return np.nan
return _norm(x, p)
def norm(x, p=2):
if not isfinite(x).all():
return np.nan
return _norm(x, p)
