TUFLOW 1D Channels and Hydraulic Structures: Difference between revisions
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| [[1D_Culverts | Culverts]]|| 1D-2D connections, flow regimes, operational control and common check files used.
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| [[1D_Bridges | Bridges]]|| Loss theory, irregular shaped bridges and common check files used. Includes links to tutorial and example models where bridges are represented in 2D.
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| [[1D_Weirs | Weirs]]|| Weir types
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== What entry/exit loss and contraction coefficients should I use for 1D culverts? ==
We don’t provide hard recommendations on the exit and entry losses to use for culverts as we have found different organisations around the world, typically government, have their own guidelines for different types of inlets configurations and require these to be used, for example, the <u>[https://www.ipwea-qnt.com/
For the entrance loss values, the approach should be to use values as quoted in the literature or guidelines for the inlet shape and design unless there is evidence to use another value (e.g. comparison with reliable calibration data would indicate different energy losses).
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A trash screen is a physical barrier, typically made from bars or mesh, placed at the inlet or outlet of a culvert, pipe, or channel to prevent debris from entering or exiting the structure.
Trash screens can be represented by applying additional head losses and blockage effects in accordance with <u>[https://www.ipwea-qnt.com/
Possible use cases include:
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For example, the image below could be represented as a rectangular shaped screen located upstream or downstream of a culvert, modelled as a short zero length RF (rectangular culvert with fixed losses) channel using a 1d_nwk GIS layer.
<ol>
[[File:Trash_screen_schematic.png|alt=|300x300px]]
</ol>
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== How can fishway baffles in a culvert be modelled? ==
Fishway baffles are barriers inside a culvert that slow the water and help fish swim through.
These approaches could be used to represent them inside a model:
* Short culvert with smaller opening.
** A short culvert section is added with its bottom and top levels set to match the fish baffle. The width is set to the total width of the fish passage gaps. This represents the reduced space for water to pass through.
* Two culverts in a row.
** Two culverts are connected in series. The first is the normal culvert, and the second is a very short culvert with a smaller opening sized to the fish baffle gaps.
For both options, sensitivity testing is recommended because at low flows the way the culvert is defined can change the results. These methods do not include turbulence or detailed 3D water movement around the baffles. If accurate fish passage flows are required, a CFD 3D model can be used to determine the flows and those flows can then be applied using a 1D Q type channel.
[[File:Rectangular culvert baffled.png|300x300px]]
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== How can a flow splitter with a nib wall be modelled? ==
A flow splitter with a nib wall can be modelled by introducing a 1D weir between the manhole and the relevant outlet pipe. The weir crest elevation should be set equal to the height of the nib wall within the chamber. This setup allows low flows to discharge through one pipe, while higher flows overtop the weir into a secondary outlet, replicating the behaviour of a physical flow splitter.
The main outlet pipes are connected through a manhole, which automatically applies appropriate entry and exit losses. For outlets that do not connect further downstream, entry and exit losses should be manually defined in the attributes.
Refer to the schematic example below for this configuration.
[[File:Manhole flow splitter topview.png|300x300px]]
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