id,summary,reporter,owner,description,type,status,priority,milestone,component,version,severity,resolution,keywords,cc 175,Compute flow through a cross section,ole,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. ",enhancement,closed,highest,,Functionality and features,,normal,fixed,,