TUFLOW 1D2D SX Advice: Difference between revisions

Selection of a 1D timestep that is too large can cause instability. The <u>[https://docs.tuflow.com/classic-hpc/manual/latest/ TUFLOW manualManual]</u> includes some discussion on 1D timestep selection and courant number criterion. Conceptually a 1D timestep should be chosen to ensure a volume of water does not travel a distance longer than the shortest 1D channel within a model. For example, if the flow velocity and celerity is 5m/s and the 1D channel length is 10 metres, the 1D timestep should be less than 2 seconds. To provide some tolerance for faster flows associated with different flood events, a timestep of 1 second may be appropriate.

2d_bc SX line features are often used to connect 1D structure to the 2D domain if the structure width is greater than one 2D cell wide (e.g. [[Tute_M02_QGIS_1d2d_Link#2d_bc_Link_as_Line_ObjectTutorial_M03|Tutorial Module02Module 03]]). This configuration not only increases the number of 1D/2D linking cells, it also has the added benefit of defining the 1D/2D boundary cells at the approximate location of the inlet/outlet of the 1D culvert. An additional benefit of this approach is that the "width" of the linking cells remains similar in length and location irrespective of 2D cell size. <br>