TUFLOW 1D Channels and Hydraulic Structures: Difference between revisions
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A scruffy dome is a type of dome inlet screen installed over a drop inlet, commonly used in stormwater systems. These inlets can be modelled in TUFLOW using a 1D Q type pit with a depth–discharge curve that reflects the hydraulic performance of the dome.
[https://www.ipwea-qnt.com/products-resources/qudm/ <u>QUDM</u>] recommends using the lesser of the weir flow or orifice flow equations to define inlet capacity (see Section 7.5.4). A blockage factor is also recommended to account for potential debris build-up during flood events (see Table 7.5.1 Provision for blockage at kerb inlets). This factor may vary depending on local guidelines, so regional standards should be consulted.
Once the rating curve is calculated, it can be added to the pit inlet database and linked to the Q type pit.
[[File:How_do_I_model_a_scruffy_dome_in_TUFLOW.png|300x300px]]<br>
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== How can trash screens be represented? ==
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
Possible use cases include:
* Where the screen is attached directly to the culvert inlet or outlet, the losses are applied to the culvert itself.
* Where the screen is located upstream of a culvert inlet or downstream of a culvert outlet, it can be modelled as a short zero length CF, IF, or RF channel before (upstream) or after (downstream) the culvert.
* In all cases, the net flow area should be reduced to account for the bars and any debris blockage, either by adjusting the flow area directly or by using the pBlockage attribute.
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.
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[[File:Trash_screen_schematic.png|alt=|300x300px]]
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== How can fishway baffles in a culvert be modelled? ==
<span style="color:red; font-weight:bold;">UNDER CONSTRUCTION</span>
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.
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[[File:Rectangular culvert baffled.png|alt=|300x300px]]
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== How can a flow splitter with a nib wall be modelled? ==
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<span style="color:red; font-weight:bold;">UNDER CONSTRUCTION</span>
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.
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[[File:Manhole flow splitter topview.png|alt=|300x300px]]
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