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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.
 
The Queensland Urban Drainage Manual (QUDM) 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.
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Where the screen is attached directly to the culvert inlet or outlet, the losses are applied to the culvert itself. For screens located upstream or downstream of the culvert, a short zero length channel should be set up as an RF (rectangular culvert with fixed losses) type in the 1d_nwk GIS layer to represent the screen. In both 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 %blockage option.
 
'''<span style="color:red">Under Construction => '''<span style="color:black">Recommended setup for representing trash screens (based on QUDM guidance).</span>'''</span>'''
{| class="wikitable"
! style="text-align:center;" | Case
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|-
| style="text-align:center;" | '''A'''
| rowspan="2" style="text-align:center;" | Inlet || Upstream of culvert inlet || Zero length RF channel before culvert || rowspan="5" | Set to net flow area<sup>1</sup> (or use %blockage) ||''K_t*'' || style="text-align:center;" | — || 0.0 (or 0.001)<sup>4</sup> || Sec. 12.5.6, Eq. 12.1 & 12.2
|-
| style="text-align:center;" | '''B''' || At culvert inlet || Losses/blockage applied to culvert ||''K_t'' (if ''K_t'' > ''K_e'') || 0.0 (or 0.001)<sup>4</sup> || style="text-align:center;" | — || Sec. 12.5.6, Eq. 12.3 – 12.5
|-
| style="text-align:center;" | '''C'''
| rowspan="3" style="text-align:center;" | Outlet || Clean screen at outlet || rowspan="3" | Zero length RF channel after culvert ||''C_d A_r'' (''C_d'' ≈ 1.5 round bars, 1.9 rectangular bars) || style="text-align:center;" | — || ''K_exit'' || Sec. 12.5.7, Eq. 12.8
|-
| style="text-align:center;" | '''D''' || Partially blocked screen at outlet || Zerorowspan="2" length RF channel after culvert ||''K_t*'' || rowspan="2" style="text-align:center;" | — || 1.0 || Sec. 12.5.7, Eq. 12.9
|-
| style="text-align:center;" | '''E''' || Downstream of outlet || Zero length RF channel after culvert ||''K_t*'' || style="text-align:center;" | — || ''K_exit'' || Sec. 12.5.7, Eq. 12.10
|}
 
'''Note:'''
 
# Net flow area should account for the effect of screen bars and any debris blockage.
# Values of ''K_t'', ''K_t*'', ''C_d'', ''A_r'', and ''K_exit'' should be obtained from the relevant QUDM equations and tables.
# ''RF'' = rectangular culvert with fixed losses. The F flag ensures specified losses are applied without default adjustments (see Table 5.2 in the <bru>[https://docs.tuflow.com/classic-hpc/manual/latest/ TUFLOW Manual]).<br/u>
# Attribute set to 0 (or 0.001 if a value of 0.0 sets this to the default value). <br><br>
 
[[File:Trash screen schematic.png|frameless]]<br><br>
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