Add 1D elements to a 2D model

1D elements can be added to any 2D model in a few simple steps. First, you need to change some Model settings, Numerical settings, and Physical settings. Then you add the 1D elements to the schematisation and upload it as a new revision. The 3Di model that is created from this revision will include the 1D elements.

Model settings to be changed

To make the required changes to the model settings, load your schematisations and open the Model settings attribute table.

In the tab Processes, check the option Use 1D flow
In the tab General, set Calculation point distance 1D to 1000. Specify the calculation point distance for each individual 1D element; this global value will then be ignored.
In the tab Advanced set Max angle advection 1D to 1.570795 radians.
In the tab General set Table step size 1D to 0.01. It is recommended to make this value much smaller than the smallest 1D cross section in the schematisation.

Numerical settings to be changed

Open the Numerical settings attribute table.

In the tab Matrix solver, set Use nested Newton to the correct value (depends on whether the 1D elements you are going to add will have open or closed cross-sections).
Still in the tab Matrix, set Convergence criterion for conjugate gradient method to “7: For 1D and 2D flow”
In the tab Slope limiters, switch the Limiter water level gradient 1D on.
In the tab Misc, the Pump implicit ratio should normally be set to 1, unless you want to study exactly when the pump switches on or off.

Physical settings to be changed

Set Use advection 1D to 3: Combined momentum and energy conservative scheme

Adding 1D elements

After having set these settings, you can start adding 1D features. See Editing schematisations for more information.

You can also add 1D elements outside of the 2D domain. Set their exchange type to isolated and connect them to a schematisation object (e.g. a channel) that does overlap with the 2D domain and has a connected or embedded exchange type.