Opened 16 years ago
Closed 16 years ago
#175 closed enhancement (fixed)
Compute flow through a cross section
Reported by: | ole | Owned by: | ole |
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Priority: | highest | Milestone: | |
Component: | Functionality and features | Version: | |
Severity: | normal | Keywords: | |
Cc: |
Description (last modified by ole)
For ANUGA to be used with flood modelling it will need a way to compute flow through an arbitrary cross section. The output, Q, would be a vector of flows for each stored timesteps. This was initially suggested by Rudy van Drie.
The function could be called as follows:
Q = flow_at_cross_section(‘model.sww’, polyline, verbose=True) Where polyline has the form [p_1, p_2, p_3, …..] and p_i = [x,y] Q is a vector of flows with units [m^3/s]
The algorithm would be as follows:
1: Obtain all intersections between polyline and triangle edges 2: From these, derive for each triangle: length of intersecting segment and its midpoint. 3: Obtain from file_function (or Interpolation_function) interpolated values for xmomentum and ymomentum at each segment midpoint. The units are [m^2/s]. 4: Compute the momentum along the normal vector of the segment at its midpoint. 5: Multiply the normal momentum with the segment length to obtain flow for that triangle. The unit is now [m^3/s]. 6: Sum up normal flows for all participating triangles and enter into Q.
A simple unit test would consist of a channel flow on a flat bed with a known inflow and the same outflow. Flow across a cross section in the channel should equal the inflow.
Issues include: What if the polyline has a corner inside a triangle? Maybe, we only do this for straight lines to begin with.
Change History (5)
comment:1 Changed 16 years ago by ole
- Description modified (diff)
comment:2 Changed 16 years ago by ole
comment:3 Changed 16 years ago by duncan
domain.flow_across_boundary('outflow_tag') seems easier, since it's using the existing mesh structure.
comment:4 Changed 16 years ago by ole
- Priority changed from normal to highest
This was raised again by Rudy 2 April 2008 and suggested as a very high priority in order for hydrological engineers to be comfortable with the correctness of the predicted flows.
comment:5 Changed 16 years ago by ole
- Resolution set to fixed
- Status changed from new to closed
First version implemented in changeset:5288
I will close this for now but reopen if issues arise when the function is tested in the wild.
Alternatively, one could implement something like
to be computed at run-time. I don't know which would be best?