TUFLOW 2D Hydraulic Structures - Revision history

Emilie Nielsen: /* 2D Layered Flow Constriction (2d_lfcsh) */

2026-04-21T23:43:05Z

2D Layered Flow Constriction (2d_lfcsh)

← Older revision		Revision as of 09:43, 22 April 2026
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	\|}		\|}
	<ol>		<ol>
	[[File:~~2d_lfcsh_attributes~~.~~png~~ \| ~~500px~~ ]]		[[File:2d_lfcsh_attributes_02.jpg\|700px]]
	</ol>		</ol>
	<br>		<br>

Emilie Nielsen: /* 2D BG Shape (2d_bg) */

2026-04-10T02:03:26Z

2D BG Shape (2d_bg)

← Older revision		Revision as of 12:03, 10 April 2026
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	2D BG Shape is similar to the Layered Flow Constriction, but has several updates to simplify the input based on the findings from the joint study with TMR <u>[https://tuflow.com/media/7554/2022-bridge-deck-afflux-modelling-benchmarking-of-cfd-and-swe-codes-to-real-world-data-collecutt-et-al-hwrs.pdf (Collecutt et al, 2022)]</u>.		2D BG Shape is similar to the Layered Flow Constriction, but has several updates to simplify the input based on the findings from the joint study with TMR <u>[https://tuflow.com/media/7554/2022-bridge-deck-afflux-modelling-benchmarking-of-cfd-and-swe-codes-to-real-world-data-collecutt-et-al-hwrs.pdf (Collecutt et al, 2022)]</u>.

	The following table provides an overview of how to determine the blockage and form loss coefficient for each layer:<br>		The following table provides an overview of how to determine the blockage and form loss coefficient for each layer. Note that this is just an overview and additional guidelines may need to be considered.<br>
	{\| style="text-align: left; margin-left: 0; " class="wikitable" width="80%"		{\| style="text-align: left; margin-left: 0; " class="wikitable" width="80%"
	!colspan="1" style="background-color:#005581; font-weight:bold; color:white;"\| Layer		!colspan="1" style="background-color:#005581; font-weight:bold; color:white;"\| Layer

Emilie Nielsen: /* 2D Layered Flow Constriction (2d_lfcsh) */

2026-04-10T02:03:08Z

2D Layered Flow Constriction (2d_lfcsh)

← Older revision		Revision as of 12:03, 10 April 2026
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	Four flow constriction layers are represented in a 2d_lfcsh layer. The lower three layers represents the pier, the bridge deck and the rails. Each layer has its own attributes to specify the blockage and the form loss coefficient. The top (fourth) layer assumes the flow is unimpeded, representative of flow over the top of a bridge. Within the same shape, the invert of the bed, and thickness of each layer can vary in 3D.		Four flow constriction layers are represented in a 2d_lfcsh layer. The lower three layers represents the pier, the bridge deck and the rails. Each layer has its own attributes to specify the blockage and the form loss coefficient. The top (fourth) layer assumes the flow is unimpeded, representative of flow over the top of a bridge. Within the same shape, the invert of the bed, and thickness of each layer can vary in 3D.

	The following table provides an overview for how to determine the blockage and form loss coefficient for each layer:<br>		The following table provides an overview for how to determine the blockage and form loss coefficient for each layer. Note that this is just an overview and additional guidelines may need to be considered.<br>
	{\| style="text-align: left; margin-left: 0; " class="wikitable" width="80%"		{\| style="text-align: left; margin-left: 0; " class="wikitable" width="80%"
	!colspan="1" style="background-color:#005581; font-weight:bold; color:white;"\| Layer		!colspan="1" style="background-color:#005581; font-weight:bold; color:white;"\| Layer

Emilie Nielsen: /* 2D BG Shape (2d_bg) */

2026-04-08T05:53:36Z

2D BG Shape (2d_bg)

← Older revision		Revision as of 15:53, 8 April 2026
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	<ol>		<ol>
	[[File:~~2d_bg_attributes~~.~~png~~ \| ~~700px~~ ]]		[[File:Bridge block.jpg \| 800px]]
	</ol>		</ol>


	===Inflection Point===		===Inflection Point===

Emilie Nielsen: /* Pier Losses */

2026-04-08T05:47:37Z

Pier Losses

← Older revision		Revision as of 15:47, 8 April 2026
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	<ol>		<ol>
	<li>Calculate the ratio of the water area occupied by piers to the gross water area of the constriction (both based on the normal water surface) and the angularity of the piers. These inputs are used to calculate "J" in the FHA documentation.</li>		<li>Calculate the ratio of the water area occupied by piers to the gross water area of the constriction (both based on the normal water surface) and the angularity of the piers. These inputs are used to calculate "J" in the FHA documentation.</li>
	<li>Use the Figure 7 ''Incremental Backwater Coefficient for Piers'' data to calculate Kp. <br>		<li>Use the Figure 4.10 ''Incremental Backwater Coefficient for Piers'' data to calculate Kp. <br>
			[[File:incremental_backwater_coefficient_2018_pier_losses.png]]
	[[File:FHA_Kp_arrow_crop.png\|400px]]
	<br>		<br>
	'''NOTE''': the pier form loss coefficients in Hydraulics of Bridge Waterways are derived based on the cross-sectional averaged velocity through the bridge opening in the absence of piers. It's not necessary to specify a blockage value if a pier form loss coefficient estimated from this method is used.		'''NOTE''': the pier form loss coefficients in Hydraulics of Bridge Waterways are derived based on the cross-sectional averaged velocity through the bridge opening in the absence of piers. It's not necessary to specify a blockage value if a pier form loss coefficient estimated from this method is used.

Emilie Nielsen: /* 2D Structure Modelling Theory */

2026-04-07T23:27:15Z

2D Structure Modelling Theory

← Older revision		Revision as of 09:27, 8 April 2026
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	= 2D Structure Modelling Theory =		= 2D Structure Modelling Theory =
	The theory behind the modelling of energy losses and affluxes of hydraulic structures is presented in the following webinars by Bill Syme and Greg Collecutt (~~the~~ TUFLOW Developers).		The theory behind the modelling of energy losses and affluxes of hydraulic structures is presented in the following webinars by Bill Syme and Greg Collecutt (TUFLOW Developers).

	*<u>[https://www.tuflow.com/library/webinars/#structures Webinar Link: Modelling Energy Losses at Structures]</u><br>		*<u>[https://www.tuflow.com/library/webinars/#structures Webinar Link: Modelling Energy Losses at Structures]</u><br>

Anne.Kolega: /* Bridge Design (hB/T) vs Form Loss Coefficient Table */

2026-03-08T22:32:18Z

Bridge Design (hB/T) vs Form Loss Coefficient Table

← Older revision		Revision as of 08:32, 9 March 2026
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	*If the hB/T ratio is less than 2 or greater than 6, use a peak form loss coefficient of 0.42 (minimum) or 0.20 (maximum), respectively.		*If the hB/T ratio is less than 2 or greater than 6, use a peak form loss coefficient of 0.42 (minimum) or 0.20 (maximum), respectively.

	'''NOTE''': This form loss value should not be confused with the value of 1.56 used in the pressure flow approached adopted in <u>[[1D_Bridges \| TUFLOW 1D "B" and "BB" bridge]]</u>. TUFLOW 1D bridge pressure flow approach is based on the section 4.13.2 "All Girders in Contact with Flow (Case II)" of ''Guide to Bridge Technology Part 8: Hydraulic Design of Waterway Structures'' (AUSTROADS, ~~2019~~). The original hydraulic experiment conducted by <u>[https://hdl.handle.net/10217/39009 Liu et al (1957)]</u> in a laboratory flume with a pair of bridge abutments and a deck. The flow conditions were similar to orifice flow due to the high blockage ratio caused by the abutments and the deck. When modelling bridges in 2D, the contraction/expansion losses caused by the abutments would be handled explicitly by the 2D solver, so a value 1.56 can lead to duplication of the contraction/expansion losses caused by the bridge abutments.<br>		'''NOTE''': This form loss value should not be confused with the value of 1.56 used in the pressure flow approached adopted in <u>[[1D_Bridges \| TUFLOW 1D "B" and "BB" bridge]]</u>. TUFLOW 1D bridge pressure flow approach is based on the section 4.13.2 "All Girders in Contact with Flow (Case II)" of ''Guide to Bridge Technology Part 8: Hydraulic Design of Waterway Structures'' (AUSTROADS, 2018). The original hydraulic experiment conducted by <u>[https://hdl.handle.net/10217/39009 Liu et al (1957)]</u> in a laboratory flume with a pair of bridge abutments and a deck. The flow conditions were similar to orifice flow due to the high blockage ratio caused by the abutments and the deck. When modelling bridges in 2D, the contraction/expansion losses caused by the abutments would be handled explicitly by the 2D solver, so a value 1.56 can lead to duplication of the contraction/expansion losses caused by the bridge abutments.<br>
	<br>		<br>

Anne.Kolega: /* 2D Structure Modelling Theory */

2026-03-08T22:20:40Z

2D Structure Modelling Theory

← Older revision		Revision as of 08:20, 9 March 2026
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	= 2D Structure Modelling Theory =		= 2D Structure Modelling Theory =
	The theory behind the modelling of energy losses and affluxes of hydraulic structures is presented in the following webinars by Bill Syme and Greg Collecutt (~~some of~~ the TUFLOW Developers).		The theory behind the modelling of energy losses and affluxes of hydraulic structures is presented in the following webinars by Bill Syme and Greg Collecutt (the TUFLOW Developers).

	*<u>[https://www.tuflow.com/library/webinars/#structures Webinar Link: Modelling Energy Losses at Structures]</u><br>		*<u>[https://www.tuflow.com/library/webinars/#structures Webinar Link: Modelling Energy Losses at Structures]</u><br>

Anne.Kolega: /* Pier Losses */

2026-03-06T04:07:23Z

Pier Losses

← Older revision		Revision as of 14:07, 6 March 2026
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	Piers are usually smaller than the 2D cell size in real-world flood models. Although flexible mesh solver or quadtree refinement can be applied to reduce the local cell size around the pier, it also comes with an expensive computational cost that could significantly increase the simulation time. More practically, the backwater effect of piers can be modelled as sub-grid form losses.		Piers are usually smaller than the 2D cell size in real-world flood models. Although flexible mesh solver or quadtree refinement can be applied to reduce the local cell size around the pier, it also comes with an expensive computational cost that could significantly increase the simulation time. More practically, the backwater effect of piers can be modelled as sub-grid form losses.

	Pier form loss coefficients can be derived from information in publications such as <u>[https://www.fhwa.dot.gov/engineering/hydraulics/library_arc.cfm?pub_number=1&id=5 ''Hydraulics of Bridge Waterways'' (Bradly, 1978)] or [https://austroads.com.au/publications/bridges/agbt08 ''Guide to Bridge Technology Part 8: Hydraulic Design of Waterway Structures'' (AUSTROADS, ~~2019~~)]</u>. Energy loss estimated from bridge piers or other obstructions, vertical or horizontal, that do not cause upstream controlled flow regimes like pressure flow, are dependent on the ratio of the obstruction's area perpendicular to the flow direction to the gross flow area of the bridge opening, the shape of the piers or obstruction, and the angularity of the piers/obstruction to the flow direction. For example, using Hydraulics of Bridge Waterways (Bradly, 1978) the approach is:		Pier form loss coefficients can be derived from information in publications such as <u>[https://www.fhwa.dot.gov/engineering/hydraulics/library_arc.cfm?pub_number=1&id=5 ''Hydraulics of Bridge Waterways'' (Bradly, 1978)] or [https://austroads.com.au/publications/bridges/agbt08 ''Guide to Bridge Technology Part 8: Hydraulic Design of Waterway Structures'' (AUSTROADS, 2018)]</u>. Energy loss estimated from bridge piers or other obstructions, vertical or horizontal, that do not cause upstream controlled flow regimes like pressure flow, are dependent on the ratio of the obstruction's area perpendicular to the flow direction to the gross flow area of the bridge opening, the shape of the piers or obstruction, and the angularity of the piers/obstruction to the flow direction. For example, using Hydraulics of Bridge Waterways (Bradly, 1978) the approach is:
	<ol>		<ol>
	<li>Calculate the ratio of the water area occupied by piers to the gross water area of the constriction (both based on the normal water surface) and the angularity of the piers. These inputs are used to calculate "J" in the FHA documentation.</li>		<li>Calculate the ratio of the water area occupied by piers to the gross water area of the constriction (both based on the normal water surface) and the angularity of the piers. These inputs are used to calculate "J" in the FHA documentation.</li>

Anne.Kolega: /* 2D Structure Modelling Theory */

2026-03-05T23:25:36Z

2D Structure Modelling Theory

← Older revision		Revision as of 09:25, 6 March 2026
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	= 2D Structure Modelling Theory =		= 2D Structure Modelling Theory =
	The theory behind the energy losses and affluxes ~~associated with the modelling~~ of hydraulic structures is presented in the following webinars by Bill Syme and Greg Collecutt (some of the TUFLOW Developers).		The theory behind the modelling of energy losses and affluxes of hydraulic structures is presented in the following webinars by Bill Syme and Greg Collecutt (some of the TUFLOW Developers).

	*<u>[https://www.tuflow.com/library/webinars/#structures Webinar Link: Modelling Energy Losses at Structures]</u><br>		*<u>[https://www.tuflow.com/library/webinars/#structures Webinar Link: Modelling Energy Losses at Structures]</u><br>