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nens / threedigrid-builder

Generate a 3Di simulation grid from a model schematisation.
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Design shadow line behaviour for junctions #275

Closed caspervdw closed 1 year ago

caspervdw commented 1 year ago

Say you have a main channel with a side channel, so a junction (connection node) that connects 3 channels. The main channel is CONNECTED and next to a levee, and it has a single shadow line to configure exchange across the it.

What happens for the exchange of the junction itself? The calculation type of the junction could be explicitly given or derived from the side channel. For ISOLATED and EMBEDDED it is clear what will happen, but for (double) CONNECTED it is unclear.

In the design of the shadow lines there is no option of specifying exchange for a manhole/connection node. So the designed behaviour is: the junction will exchange with the 2D cell where the junction is. I guess that makes sense in case the side channel has no exchange line (but exchanging accross the levee would have made equal sense)

But what if the side channel also has an exchange line? Then only the junction will not exchange across a levee.

caspervdw commented 1 year ago

One option is as follows:

  1. The junction derives the exchange lines of the first (lowest id) connected channel. If it is double connected, it only derives the exchange lines from double connected channels. If there are not sufficient exchange lines (e.g. only connected channels with a double connected junction), the junction exchanges with the cell it is located in.
  2. If there is a breach line at the junction, it precedes. For double connected junctions with 1 breach line, we can pick the channel of the breach line for the other exchange direction (see point 1.)