def __init__(self,
domain,
polyline=None,
verbose=False):
"""Create an instance of Cross_section.
domain domain of interest
polyline polyline defining cross section
verbose True if this instance is to be verbose
"""
self.domain = domain
self.polyline = polyline
self.verbose = verbose
# Find all intersections and associated triangles.
self.segments = self.domain.get_intersecting_segments(self.polyline,
use_cache=True,
verbose=self.verbose)
# Get midpoints
self.midpoints = segment_midpoints(self.segments)
# Make midpoints Geospatial instances
self.midpoints = ensure_geospatial(self.midpoints, self.domain.geo_reference)
def get_interpolated_quantities_at_polyline_midpoints(filename,
quantity_names=None,
polyline=None,
verbose=False):
"""Get values for quantities interpolated to polyline midpoints from SWW.
filename path to file to read
quantity_names quantity names to get
polyline representation of desired cross-section
may contain multiple sections allowing complex shapes
assume UTM coordinates
verbose True if this function is to be verbose
Returns (segments, i_func)
where segments is a list of Triangle_intersection instances
and i_func is an instance of Interpolation_function.
Note: For 'polyline' assume absolute UTM coordinates.
This function is used by get_flow_through_cross_section and
get_energy_through_cross_section.
"""
from anuga.fit_interpolate.interpolate import Interpolation_function
# Get mesh and quantities from sww file
X = get_mesh_and_quantities_from_file(filename,
quantities=quantity_names,
verbose=verbose)
mesh, quantities, time = X
# Find all intersections and associated triangles.
segments = mesh.get_intersecting_segments(polyline, verbose=verbose)
# Get midpoints
interpolation_points = segment_midpoints(segments)
# Interpolate
if verbose:
log.critical(
'Interpolating - total number of interpolation points = %d' %
len(interpolation_points))
I = Interpolation_function(time,
quantities,
quantity_names=quantity_names,
vertex_coordinates=mesh.nodes,
triangles=mesh.triangles,
interpolation_points=interpolation_points,
verbose=verbose)
return segments, I
def get_interpolated_quantities_at_polyline_midpoints(filename,
quantity_names=None,
polyline=None,
verbose=False):
"""Get values for quantities interpolated to polyline midpoints from SWW.
filename path to file to read
quantity_names quantity names to get
polyline representation of desired cross-section
may contain multiple sections allowing complex shapes
assume UTM coordinates
verbose True if this function is to be verbose
Returns (segments, i_func)
where segments is a list of Triangle_intersection instances
and i_func is an instance of Interpolation_function.
Note: For 'polyline' assume absolute UTM coordinates.
This function is used by get_flow_through_cross_section and
get_energy_through_cross_section.
"""
from anuga.fit_interpolate.interpolate import Interpolation_function
# Get mesh and quantities from sww file
X = get_mesh_and_quantities_from_file(filename,
quantities=quantity_names,
verbose=verbose)
mesh, quantities, time = X
# Find all intersections and associated triangles.
segments = mesh.get_intersecting_segments(polyline, verbose=verbose)
# Get midpoints
interpolation_points = segment_midpoints(segments)
# Interpolate
if verbose:
log.critical('Interpolating - total number of interpolation points = %d'
% len(interpolation_points))
I = Interpolation_function(time,
quantities,
quantity_names=quantity_names,
vertex_coordinates=mesh.nodes,
triangles=mesh.triangles,
interpolation_points=interpolation_points,
verbose=verbose)
return segments, I
def get_flow_through_cross_section(filename, polyline, verbose=False):
"""Obtain flow (m^3/s) perpendicular to specified cross section.
filename path to SWW file to read
polyline representation of desired cross-section - it may contain
multiple sections allowing for complex shapes. Assume
absolute UTM coordinates.
Format [[x0, y0], [x1, y1], ...]
verbose True if this function is to be verbose
Return (time, Q)
where time is a list of all stored times in SWW file
and Q is a hydrograph of total flow across given segments for all
stored times.
The normal flow is computed for each triangle intersected by the polyline
and added up. Multiple segments at different angles are specified the
normal flows may partially cancel each other.
The typical usage of this function would be to get flow through a channel,
and the polyline would then be a cross section perpendicular to the flow.
"""
print 'In get_flow_through_cross_section'
quantity_names =['elevation',
'stage',
'xmomentum',
'ymomentum']
# Get values for quantities at each midpoint of poly line from sww file
# X = get_interpolated_quantities_at_polyline_midpoints(filename,
# quantity_names=\
# quantity_names,
# polyline=polyline,
# verbose=verbose)
from anuga.fit_interpolate.interpolate import Interpolation_function
print 'In get_interpolated_quantities_at_polyline_midpoints'
# Get mesh and quantities from sww file
X = get_mesh_and_quantities_from_file(filename,
quantities=quantity_names,
verbose=verbose)
mesh, quantities, time = X
# Find all intersections and associated triangles.
segments = mesh.get_intersecting_segments(polyline, verbose=verbose)
# Get midpoints
interpolation_points = segment_midpoints(segments)
# Interpolate
if verbose:
print 'Interpolating - total number of interpolation points = %d' % len(interpolation_points)
interpolation_function = Interpolation_function(time,
quantities,
quantity_names=quantity_names,
vertex_coordinates=mesh.nodes,
triangles=mesh.triangles,
interpolation_points=interpolation_points,
verbose=verbose)
# Get vectors for time and interpolation_points
time = interpolation_function.time
interpolation_points = interpolation_function.interpolation_points
if verbose: print 'Computing hydrograph'
# Compute hydrograph
Q = []
for t in time:
total_flow = 0
for i in range(len(interpolation_points)):
elevation, stage, uh, vh = interpolation_function(t, point_id=i)
normal = segments[i].normal
# Inner product of momentum vector with segment normal [m^2/s]
normal_momentum = uh*normal[0] + vh*normal[1]
# Flow across this segment [m^3/s]
segment_flow = normal_momentum * segments[i].length
# Accumulate
total_flow += segment_flow
# Store flow at this timestep
Q.append(total_flow)
return time, Q
