1D Syphons: Difference between revisions

ThereWhilst TUFLOW does have a specific syphon channel, there are two approaches to model a syphon system in TUFLOW.

The most appropriate approach to model a syphon is to use a M channel, described in Section 5.8.1 ''M Channels (User Defined Flow Matrix)'' in the, <u>[https://downloads.tuflow.com/TUFLOW/Releases/Latest/TUFLOW%20Manual.pdf TUFLOW user Manualmanual]</u>. AnA M channel can be used to define a matrix of flows between two invert levels based on their respective depths. If this matrix of flows through the syphon can be calculated, or if they are given as part of the operational instructions, then they can be input in .csv form as below, where negative values indicate flows going from downstream to upstream.

Alternatively, 1d_nwk nodes can be used to account for the storage of the vertical portion of the syphon as the images shown below. This configuration essentially estimates the flows conveyed though the syphon based on the upstream and downstream water level and the hydraulic property of the bottom pipe. YouIt can probably account for the bend loss (or any extra loss) through the syphon using the Form_Loss attribute of the pipe. It’sis strongly recommended to calibrate the model result against measurement data to check the accuracy or if measurement data are not available, conduct sensitivity testing.

TheFor this method, the main losses for a syphon areshould be considered:

* entry and exit losses (let tuflow calculate it automatically)

* friction at pipe and wall (use manning's n)

* bend losslosses