TUFLOW 2D Hydraulic Structures: Difference between revisions

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== What is the difference between using polyline and polygon for 2D bridges and when should I use them? ==

When using 2d_lfcsh, the form loss coefficient (FLC) is applied differently when using a line compared to a polygon. The FLC is applied at cell sides (u and v points) as this is where velocities are calculated.

The form loss parameters can be transferred from the flow constriction (2d_fc or 2d_fcsh) to the first layer of the layered flow constriction (2d_lfcsh). Definition of the remaining form loss and blockage layer inputs in the 2d_lfcsh should follow the guidance outlined in <u>[[TUFLOW_FAQ#What_form_loss_coefficient_.28FLC.29_values_should_I_use_for_2d_lfcsh_bridge.3F | What form loss coefficient (FLC) values should I use for 2d lfcsh bridge?]]</u> paragraph.<br>

When using floating pontoon (type FD in the 2d_fc or 2d_fcsh) different setup might need to be used for different events. For large events when floating pontoon becomes fixed at the top of the supporting piles, standard 2d_lfcsh setup can be used. Smaller events when the pontoon is floating at different heights might require more sensitivity testing of the structure parameters to find out a setup the matches the reality as close as possible.<br>