TUFLOW 2D Hydraulic Structures: Difference between revisions
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| 1 || Pier layer || ~5% (can be omitted if included in FLC) || Estimate using <u>[[TUFLOW_2D_Hydraulic_Structures#Pier_Losses | Pier Losses]]</u> || Represents flow obstruction from piers beneath the bridge deck
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| 2 || Bridge deck || 100% || Use calibration data, if available, to determine FLC. <br> If no calibration is available, estimate using <u>[[TUFLOW_2D_Hydraulic_Structures#Bridge_Design_.28hB.2FT.29_vs_Form_Loss_Coefficient_Table | hB/T vs FLC]]</u> table || Full blockage, no flow through the deck
If using the <u>[[TUFLOW_2D_Hydraulic_Structures#Bridge_Design_.28hB.2FT.29_vs_Form_Loss_Coefficient_Table | hB/T vs FLC]]</u> table, it is recommended to enable the Method C Form Loss Approach
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| 3 || Bridge rails || 10% – 100% || Use calibration data, if available, to determine FLC. <br>
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*L2 FLC and L3 FLC should sum to the combined FLC
|Blockage and FLC depends on rail type <br> Sensitivity testing with 100% blockage is recommended due to potential for debris during flood
If using the <u>[[TUFLOW_2D_Hydraulic_Structures#Bridge_Design_.28hB.2FT.29_vs_Form_Loss_Coefficient_Table | hB/T vs FLC]]</u> table, it is recommended to enable the Method C Form Loss Approach
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| 4 || Above rails || 0% || 0 || Represents unimpeded overtopping flow
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| Thick
| between zero and 1.5 times the cell size
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| FLC/2 applied to all sides of the selected cells
| A cell is selected if the polyline intersects the cell crosshair. Caution should be taken when using a "thick" line, as changes in cell size can cause it to become a "wide" line. If this occurs, the FLC attribute
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| Wide
| larger than 1.5 times the cell size
| Total form loss
| FLC divided by number of cell sides in the direction of flow <br>
''(number of cell sides in the direction of flow is calculated as line width divided by cell size)''
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Caution should be taken when using a "wide" line. The cell size and alignment of the 2d_lfcsh line may result in selecting too many or too few cell faces in the direction of the flow. The FLC input may need to be recalculated to ensure FLC Applied multiplied by the number of cell sides in the direction of flow equates to the intended total form loss.
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!rowspan="1" | Polygon
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<br>
The following diagrams demonstrate how the input FLC is applied for the four geometry options for 2d_lfcsh and 2d_bg layers: <br>
[[File:2dlfcsh 2dbg combined v2.png|1200px]]
It is good modelling practice to check the <u>[[Check_Files_2d_lfcsh_uvpt | lfcsh_uvpt_check]]</u> and <u>[[Check Files 2d bg uvpt check | bg_uvpt_check]]</u> files to confirm the number of faces selected and the FLC values assigned. It is also strongly recommended to undertake a sensitivity analysis on the applied form losses in the model to check if it makes any difference to the results and/or double check against other methods (hand calculations, other software, CFD modelling), especially if the bridge is near an area of interest. If calibration data is available, this should be used to guide the form loss value specification.<br>
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