TUFLOW General Discussion - Revision history

Teegan.Burke: /* What is the difference between single and double precision and when should I use them? */

2026-05-26T05:07:25Z

What is the difference between single and double precision and when should I use them?

← Older revision		Revision as of 15:07, 26 May 2026
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	*The coupled TUFLOW 1D engine requires the use of the double precision solver to achieve better stability in 1D with more significant numbers. This usually happens with 1D/2D models with ground elevation greater than 100m (TUFLOW 1D engine uses water level as the primary variable as TUFLOW Classic), carved 1D channels within the 2D domain where either the 1D channel itself or the boundary links between 1D and 2D domain can cause the mass error. *On rare occasions, models with higher elevations and small QT inflow would require double precision, because QT boundaries have hidden 1D node and as such are solved in the TUFLOW 1D engine.		*The coupled TUFLOW 1D engine requires the use of the double precision solver to achieve better stability in 1D with more significant numbers. This usually happens with 1D/2D models with ground elevation greater than 100m (TUFLOW 1D engine uses water level as the primary variable as TUFLOW Classic), carved 1D channels within the 2D domain where either the 1D channel itself or the boundary links between 1D and 2D domain can cause the mass error. *On rare occasions, models with higher elevations and small QT inflow would require double precision, because QT boundaries have hidden 1D node and as such are solved in the TUFLOW 1D engine.
	***When the simulation time is long or the model has large Start Time value (more than 100000.0 hours), the around up issue can happen to the simulation time because the model timestep is typically in the order of 0.1~10 seconds. This might cause issues in reading and outputting boundary data.		***When the simulation time is long or the model has large Start Time value (more than 100000.0 hours), the around up issue can happen to the simulation time because the model timestep is typically in the order of 0.1~10 seconds. This might cause issues in reading and outputting boundary data.
			***When very small inflow or outflows are applied, for example when representing evapotranspiration or the tail ends of storm events.

	The single precision version of TUFLOW uses significantly less memory (RAM) and is about 20% faster for TUFLOW Classic and four times faster for HPC. Unless required otherwise, the single precision version of TUFLOW is recommended. A good step in the model development is to run the model with both the single and the double precision and if the results / mass balance are similar then the single precision version is sufficient.<br>		The single precision version of TUFLOW uses significantly less memory (RAM) and is about 20% faster for TUFLOW Classic and four times faster for HPC. Unless required otherwise, the single precision version of TUFLOW is recommended. A good step in the model development is to run the model with both the single and the double precision and if the results / mass balance are similar then the single precision version is sufficient.<br>

Emilie Nielsen: /* How closely do TUFLOW results match other hydraulic software? */

2024-07-18T04:24:57Z

How closely do TUFLOW results match other hydraulic software?

← Older revision		Revision as of 14:24, 18 July 2024
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	Different software will give different results for the simple reason that they all include different calculation assumptions. Understanding what those assumptions are and how they influence results will be important for the sensitivity testing.		Different software will give different results for the simple reason that they all include different calculation assumptions. Understanding what those assumptions are and how they influence results will be important for the sensitivity testing.
	TUFLOW, like all hydraulic modelling software, needs to be applied appropriately and models should be calibrated to real world events if calibration data are available. The three pillars of TUFLOW's development focus are solution accuracy, simulation speed, workflow efficient. Extensive benchmarking globally have demonstrated TUFLOW is top in its class in all three categories. Helpful software support, coupling with 1D and integration with GIS also needs to be considered as it is very important for many users.<br>		TUFLOW, like all hydraulic modelling software, needs to be applied appropriately and models should be calibrated to real world events if calibration data are available. The three pillars of TUFLOW's development focus are solution accuracy, simulation speed, workflow efficient. Extensive benchmarking globally have demonstrated TUFLOW is top in its class in all three categories. Helpful software support, coupling with 1D and integration with GIS also needs to be considered as it is very important for many users.<br>
	The <u>[~~https~~://book.arr.org.au.s3-website-ap-southeast-2.amazonaws.com/ Australian Rainfall and Runoff document]</u> has a good section in Book 6 on flood hydraulics. This discusses difference in solution scheme such as finite difference, finite volume, finite element, and implicit versus explicit.		The <u>[http://book.arr.org.au.s3-website-ap-southeast-2.amazonaws.com/ Australian Rainfall and Runoff document]</u> has a good section in Book 6 on flood hydraulics. This discusses difference in solution scheme such as finite difference, finite volume, finite element, and implicit versus explicit.
	<br>		<br>

Emilie Nielsen at 04:22, 18 July 2024

2024-07-18T04:22:47Z

← Older revision		Revision as of 14:22, 18 July 2024
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	Different software will give different results for the simple reason that they all include different calculation assumptions. Understanding what those assumptions are and how they influence results will be important for the sensitivity testing.		Different software will give different results for the simple reason that they all include different calculation assumptions. Understanding what those assumptions are and how they influence results will be important for the sensitivity testing.
	TUFLOW, like all hydraulic modelling software, needs to be applied appropriately and models should be calibrated to real world events if calibration data are available. The three pillars of TUFLOW's development focus are solution accuracy, simulation speed, workflow efficient. Extensive benchmarking globally have demonstrated TUFLOW is top in its class in all three categories. Helpful software support, coupling with 1D and integration with GIS also needs to be considered as it is very important for many users.<br>		TUFLOW, like all hydraulic modelling software, needs to be applied appropriately and models should be calibrated to real world events if calibration data are available. The three pillars of TUFLOW's development focus are solution accuracy, simulation speed, workflow efficient. Extensive benchmarking globally have demonstrated TUFLOW is top in its class in all three categories. Helpful software support, coupling with 1D and integration with GIS also needs to be considered as it is very important for many users.<br>
	The <u>[~~http~~://book.arr.org.au.s3-website-ap-southeast-2.amazonaws.com/ Australian Rainfall and Runoff document]</u> has a good section in Book 6 on flood hydraulics. This discusses difference in solution scheme such as finite difference, finite volume, finite element, and implicit versus explicit.		The <u>[https://book.arr.org.au.s3-website-ap-southeast-2.amazonaws.com/ Australian Rainfall and Runoff document]</u> has a good section in Book 6 on flood hydraulics. This discusses difference in solution scheme such as finite difference, finite volume, finite element, and implicit versus explicit.
	<br>		<br>

Tuflowduncan: /* Can TUFLOW model non-water liquids? */

2023-09-11T15:15:30Z

Can TUFLOW model non-water liquids?

← Older revision		Revision as of 01:15, 12 September 2023
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	:<font color="blue"><tt>Viscosity Coefficients </tt></font><font color="red"><tt>== </tt></font>k, n, muLow, muHigh, tau0		:<font color="blue"><tt>Viscosity Coefficients </tt></font><font color="red"><tt>== </tt></font>k, n, muLow, muHigh, tau0

	Where k is the viscosity coefficient in Pa.s when n = 1. Where n=1, this relates to a Newtonian fluid. You can then use an appropriate value for tau0, the stress required to make the fluid move. The Non-Newtonian model uses the Herschel-Bulkley approach which can be used to model Newtonian fluids with different viscosities. See section 5.4 of the <u>[https://downloads.tuflow.com/TUFLOW/Releases/2020-10/TUFLOW%20Release%20Notes.2020-10-AD.pdf 2020 Release Notes]</u> for more information.		Where k is the viscosity coefficient in Pa.s when ''n'' = 1. Where ''n''=1, this relates to a Newtonian fluid. You can then use an appropriate value for tau0, the stress required to make the fluid move. The Non-Newtonian model uses the Herschel-Bulkley approach which can be used to model Newtonian fluids with different viscosities. See section 5.4 of the <u>[https://downloads.tuflow.com/TUFLOW/Releases/2020-10/TUFLOW%20Release%20Notes.2020-10-AD.pdf 2020 Release Notes]</u> for more information.

	The graphs below explains the Herschel-Bulkley approach and it’s flexibility:		The graphs below explains the Herschel-Bulkley approach and it’s flexibility:

Tuflowduncan: /* Can TUFLOW model non-water liquids? */

2023-09-11T15:14:53Z

Can TUFLOW model non-water liquids?

← Older revision		Revision as of 01:14, 12 September 2023
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	:[[File:Formula 004.PNG \| 130px]]		:[[File:Formula 004.PNG \| 130px]]

	It should be seen that where Ƭ0=0, the Herschel-Bulkley equation is the same as the power law model. If n is 1, then the Herschel-Bulkley equation is the same as the Bingham Plastic model. If Ƭ0=0 and n =1, then the Herschel-Bulkley equation is the same as the Newtonian fluid approach. By using the Herschel-Bulkley equation as a Newtonian model, it does allow you to define the viscosity coefficient for the fluid. In ~~your~~ ~~case~~ ~~you’ll~~ need to convert the viscosity from centiStokes to Pa S (if using an N value of 1). ~~You~~ ~~can~~ ~~then~~ define the fluid density using the <font color="blue"><tt>Density of Water</tt></font> command ~~you mention~~.		It should be seen that where ''Ƭ<sub>0</sub>=''0, the Herschel-Bulkley equation is the same as the power law model. If ''n'' is 1, then the Herschel-Bulkley equation is the same as the Bingham Plastic model. If ''Ƭ<sub>0</sub>''=0 and ''n'' =1, then the Herschel-Bulkley equation is the same as the Newtonian fluid approach. By using the Herschel-Bulkley equation as a Newtonian model, it does allow you to define the viscosity coefficient for the fluid. There may be a need to convert the viscosity from centiStokes to Pa S (if using an ''n'' value of 1). It is also possible to define the fluid density using the <font color="blue"><tt>Density of Water</tt></font> command.

	You can test this out using the following commands.		You can test this out using the following commands.
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	:<font color="blue"><tt>Viscosity Coefficients </tt></font><font color="red"><tt>== </tt></font>0.001, 1, 0.0, 1000, 0		:<font color="blue"><tt>Viscosity Coefficients </tt></font><font color="red"><tt>== </tt></font>0.001, 1, 0.0, 1000, 0

	This uses a n value of 1, a Ƭ0=0 and a viscosity coefficient of 0.001 Pa S which is a typical viscosity of water at 20 ℃. This should give comparable outputs to a standard TUFLOW model without the Non-Newtonian functionality.		This uses a ''n'' value of 1, a ''Ƭ<sub>0</sub>''=0 and a viscosity coefficient of 0.001 Pa S which is a typical viscosity of water at 20 ℃. This should give comparable outputs to a standard TUFLOW model without the Non-Newtonian functionality.

	== How closely do TUFLOW results match other hydraulic software? ==		== How closely do TUFLOW results match other hydraulic software? ==

Pavlina Monhartova: /* Can TUFLOW's 1D engine be used for modelling complex pipe hydraulics? */

2023-03-01T05:14:19Z

Can TUFLOW's 1D engine be used for modelling complex pipe hydraulics?

← Older revision		Revision as of 15:14, 1 March 2023
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	* The 2020 TUFLOW release offers sub-grid topography sampling to process all elevations within the cell into a depth/volume relationship for its calculations. This approach ensures much more accurate water depth estimations at pit inlets, even if the 2D cell resolution is much larger than the geometry of the drain at the inlet. This in turn translates to more accurate representation of the pit inflow, and as such flow through the entire pipe network. No other 1D/2D stormwater drainage modelling software offers this functionality. The new Quadtree functionality also allows the user to model key flowpaths, such as road drains, in high resolution.		* The 2020 TUFLOW release offers sub-grid topography sampling to process all elevations within the cell into a depth/volume relationship for its calculations. This approach ensures much more accurate water depth estimations at pit inlets, even if the 2D cell resolution is much larger than the geometry of the drain at the inlet. This in turn translates to more accurate representation of the pit inflow, and as such flow through the entire pipe network. No other 1D/2D stormwater drainage modelling software offers this functionality. The new Quadtree functionality also allows the user to model key flowpaths, such as road drains, in high resolution.
	* The 2D overland approach used by TUFLOW ensures any above ground inundation is defined by the model topography. This approach avoids any engineering judgement flow path definition mistakes which the 1D overland software suffer from.<br>		* The 2D overland approach used by TUFLOW ensures any above ground inundation is defined by the model topography. This approach avoids any engineering judgement flow path definition mistakes which the 1D overland software suffer from.<br>
	* The network schematisation technique used by TUFLOW 1D allows realistic simulation of a wide variety of 1D and quasi-2D situations including: complex river geometries; associated floodplains and estuaries; and urban channel and pipe network systems. There is a considerable amount of flexibility in the way network elements can be interconnected, allowing the representation of a river and floodplain by many parallel channels with different resistance characteristics and the simulation of braided streams and rivers with complex branching. This flexibility also allows a variable resolution within the network so that areas of particular interest can be modelled in fine detail, with a coarser network representation being used elsewhere.		* In addition, TUFLOW' s 1D solver (ESTRY) solves the full one-dimensional (1D) free-surface St Venant flow equations using a Runge-Kutta explicit solver. TUFLOW 1D has seen continuous development since 1972.The network schematisation technique used by TUFLOW 1D allows realistic simulation of a wide variety of 1D and quasi-2D situations including: complex river geometries; associated floodplains and estuaries; and urban channel and pipe network systems. There is a considerable amount of flexibility in the way network elements can be interconnected, allowing the representation of a river and floodplain by many parallel channels with different resistance characteristics and the simulation of braided streams and rivers with complex branching. This flexibility also allows a variable resolution within the network so that areas of particular interest can be modelled in fine detail, with a coarser network representation being used elsewhere.

	==Can TUFLOW model flows in steep slopes accurately?==		==Can TUFLOW model flows in steep slopes accurately?==

Pavlina Monhartova: /* Can TUFLOW's 1D engine be used for modelling complex pipe hydraulics? */

2023-03-01T05:12:38Z

Can TUFLOW's 1D engine be used for modelling complex pipe hydraulics?

← Older revision		Revision as of 15:12, 1 March 2023
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	** variation in pipe approach and exit angles at junctions		** variation in pipe approach and exit angles at junctions
	** variation in pipe approach and exit elevation at junctions		** variation in pipe approach and exit elevation at junctions
	* Alternative loss methods to Engelund are also available, such as Fixed losses. The Fixed method conforms with some industry guidelines, such as the Qld Urban Drainage Manual (QUDM). Fixed losses are not set as the default as this generally requires the modeller to manually enter appropriate values at every manhole, whereas the Engelund approach in TUFLOW, which is based on that in MIKE Urban with several improvements developed in conjunction with Gold Coast City Council’s infrastructure team, provides an excellent automatic approach with no or minimal user input beyond the pipe and manhole geometry. The other advantage of the Engelund approach is that it is dynamic and adjusts losses according to the flow conditions, whereas the Fixed approach assumes the same energy loss coefficient for all flow regimes. TUFLOW also allows having a mix of different methods in the one model, for example, there may be a special manhole where the Fixed or other approach needs to be applied.		* Alternative loss methods to Engelund are also available, such as Fixed losses. The Fixed method conforms with some industry guidelines, such as the Qld Urban Drainage Manual (QUDM). Fixed losses are not set as the default as this generally requires the modeller to manually enter appropriate values at every manhole, whereas the Engelund approach in TUFLOW, which is based on that in MIKE Urban with several improvements developed in conjunction with Gold Coast City Council’s infrastructure team, provides an excellent automatic approach with no or minimal user input beyond the pipe and manhole geometry. The other advantage of the Engelund approach is that it is dynamic and adjusts losses according to the flow conditions, whereas the Fixed approach assumes the same energy loss coefficient for all flow regimes. TUFLOW also allows having a mix of different methods in the one model, for example, there may be a special manhole where the Fixed or other approach needs to be applied.
	* There are numerous pit inlet options, from automatic capture rates to manually defined depth-discharge relationships. In all cases the 2D cell water depth at the inlet influences the amount of flow entering the pit, and as such the 1D underground pipe network.		* There are numerous pit inlet options, from automatic capture rates to manually defined depth-discharge relationships. In all cases the 2D cell water depth at the inlet influences the amount of flow entering the pit, and as such the 1D underground pipe network.
	* The 2020 TUFLOW release offers sub-grid topography sampling to process all elevations within the cell into a depth/volume relationship for its calculations. This approach ensures much more accurate water depth estimations at pit inlets, even if the 2D cell resolution is much larger than the geometry of the drain at the inlet. This in turn translates to more accurate representation of the pit inflow, and as such flow through the entire pipe network. No other 1D/2D stormwater drainage modelling software offers this functionality. The new Quadtree functionality also allows the user to model key flowpaths, such as road drains, in high resolution.		* The 2020 TUFLOW release offers sub-grid topography sampling to process all elevations within the cell into a depth/volume relationship for its calculations. This approach ensures much more accurate water depth estimations at pit inlets, even if the 2D cell resolution is much larger than the geometry of the drain at the inlet. This in turn translates to more accurate representation of the pit inflow, and as such flow through the entire pipe network. No other 1D/2D stormwater drainage modelling software offers this functionality. The new Quadtree functionality also allows the user to model key flowpaths, such as road drains, in high resolution.
	* The 2D overland approach used by TUFLOW ensures any above ground inundation is defined by the model topography. This approach avoids any engineering judgement flow path definition mistakes which the 1D overland software suffer from.<br>		* The 2D overland approach used by TUFLOW ensures any above ground inundation is defined by the model topography. This approach avoids any engineering judgement flow path definition mistakes which the 1D overland software suffer from.<br>
			* The network schematisation technique used by TUFLOW 1D allows realistic simulation of a wide variety of 1D and quasi-2D situations including: complex river geometries; associated floodplains and estuaries; and urban channel and pipe network systems. There is a considerable amount of flexibility in the way network elements can be interconnected, allowing the representation of a river and floodplain by many parallel channels with different resistance characteristics and the simulation of braided streams and rivers with complex branching. This flexibility also allows a variable resolution within the network so that areas of particular interest can be modelled in fine detail, with a coarser network representation being used elsewhere.

	==Can TUFLOW model flows in steep slopes accurately?==		==Can TUFLOW model flows in steep slopes accurately?==

Pavlina Monhartova at 00:57, 1 March 2023

2023-03-01T00:57:21Z

← Older revision		Revision as of 10:57, 1 March 2023
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	== How to do hydraulic modelling with scarce site data? ==		== How to do hydraulic modelling with scarce site data? ==
	The best thing to do in this case is to build the model using industry standard values. Do sensitivity testing of model inputs to identify if the results change dramatically due to the modelling choices, e.g. cell sizes, inflows, boundary influences. After building the model, any opportunity to conduct community consultation is usually well worthwhile as the locals will have a feel whether the model is demonstrating the flood behavior they have observed. For more information see <u>[https://www.tuflow.com/library/webinars/#maximise_accuracy Maximising the Accuracy of Hydraulic Model webinar]</u>.<br>		The best thing to do in this case is to build the model using industry standard values. Do sensitivity testing of model inputs to identify if the results change dramatically due to the modelling choices, e.g. cell sizes, inflows, boundary influences. After building the model, any opportunity to conduct community consultation is usually well worthwhile as the locals will have a feel whether the model is demonstrating the flood behavior they have observed. For more information see <u>[https://www.tuflow.com/library/webinars/#maximise_accuracy Maximising the Accuracy of Hydraulic Model webinar]</u>.<br>

	== Can I use SRTM data for modelling rivers if no other sources are available? ==
	SRTM is a very coarse grid. May be suitable of catchment discretisation of large catchments (100km2+) but generally should never be used for 1D or 2D flood modelling. For river bathymetry, SRTM or LiDAR won't penetrate accurately below the water surface so ground survey or bathymetric survey will be required. For the floodplain SRTM data may able to be used, provided its vertical accuracy is checked against ground survey data (SRTM is usually very inaccurate in the vertical). For this reason, approaching local agencies if they have bathymetry data (Local Council, County or State Department) might be the next step. In some countries these agencies host the data online for download.<br>

	<br>		<br>

Pavlina Monhartova: /* How to do hydraulic modelling with scarce site data? */

2023-03-01T00:54:41Z

How to do hydraulic modelling with scarce site data?

← Older revision		Revision as of 10:54, 1 March 2023
Line 122:		Line 122:
	== How to do hydraulic modelling with scarce site data? ==		== How to do hydraulic modelling with scarce site data? ==
	The best thing to do in this case is to build the model using industry standard values. Do sensitivity testing of model inputs to identify if the results change dramatically due to the modelling choices, e.g. cell sizes, inflows, boundary influences. After building the model, any opportunity to conduct community consultation is usually well worthwhile as the locals will have a feel whether the model is demonstrating the flood behavior they have observed. For more information see <u>[https://www.tuflow.com/library/webinars/#maximise_accuracy Maximising the Accuracy of Hydraulic Model webinar]</u>.<br>		The best thing to do in this case is to build the model using industry standard values. Do sensitivity testing of model inputs to identify if the results change dramatically due to the modelling choices, e.g. cell sizes, inflows, boundary influences. After building the model, any opportunity to conduct community consultation is usually well worthwhile as the locals will have a feel whether the model is demonstrating the flood behavior they have observed. For more information see <u>[https://www.tuflow.com/library/webinars/#maximise_accuracy Maximising the Accuracy of Hydraulic Model webinar]</u>.<br>

			== Can I use SRTM data for modelling rivers if no other sources are available? ==
			SRTM is a very coarse grid. May be suitable of catchment discretisation of large catchments (100km2+) but generally should never be used for 1D or 2D flood modelling. For river bathymetry, SRTM or LiDAR won't penetrate accurately below the water surface so ground survey or bathymetric survey will be required. For the floodplain SRTM data may able to be used, provided its vertical accuracy is checked against ground survey data (SRTM is usually very inaccurate in the vertical). For this reason, approaching local agencies if they have bathymetry data (Local Council, County or State Department) might be the next step. In some countries these agencies host the data online for download.<br>

	<br>		<br>

Pavlina Monhartova: /* How closely do TUFLOW results match other hydraulic software? */

2023-03-01T00:50:37Z

How closely do TUFLOW results match other hydraulic software?

← Older revision		Revision as of 10:50, 1 March 2023
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	== How closely do TUFLOW results match other hydraulic software? ==		== How closely do TUFLOW results match other hydraulic software? ==
	Different software will give different results for the simple reason that they all include different calculation assumptions. Understanding what those assumptions are and how they influence results will be important for the sensitivity testing.		Different software will give different results for the simple reason that they all include different calculation assumptions. Understanding what those assumptions are and how they influence results will be important for the sensitivity testing.
	TUFLOW, like all hydraulic modelling software, needs to be applied appropriately and models should be calibrated to real world events if calibration data are available. The three pillars of TUFLOW's development focus are solution accuracy, simulation speed, workflow efficient. Extensive benchmarking globally have demonstrated TUFLOW is top in its class in all three categories. Helpful software support also needs to be considered as it is very important for many users.<br>		TUFLOW, like all hydraulic modelling software, needs to be applied appropriately and models should be calibrated to real world events if calibration data are available. The three pillars of TUFLOW's development focus are solution accuracy, simulation speed, workflow efficient. Extensive benchmarking globally have demonstrated TUFLOW is top in its class in all three categories. Helpful software support, coupling with 1D and integration with GIS also needs to be considered as it is very important for many users.<br>
	The <u>[http://book.arr.org.au.s3-website-ap-southeast-2.amazonaws.com/ Australian Rainfall and Runoff document]</u> has a good section in Book 6 on flood hydraulics. This discusses difference in solution scheme such as finite difference, finite volume, finite element, and implicit versus explicit.		The <u>[http://book.arr.org.au.s3-website-ap-southeast-2.amazonaws.com/ Australian Rainfall and Runoff document]</u> has a good section in Book 6 on flood hydraulics. This discusses difference in solution scheme such as finite difference, finite volume, finite element, and implicit versus explicit.
	<br>		<br>