TUFLOW Stability Troubleshooting - Revision history

Teegan.Burke at 04:34, 16 December 2025

2025-12-16T04:34:50Z

← Older revision		Revision as of 14:34, 16 December 2025
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	* Connect cells that have a constant water level (perpendicular to flow) as the water level boundary will be averaged from the connected cells. Connecting cells that are not perpendicular to the flow could mean the average water level upstream of the culvert to be higher that in reality and downstream average water level will be lower.		* Connect cells that have a constant water level (perpendicular to flow) as the water level boundary will be averaged from the connected cells. Connecting cells that are not perpendicular to the flow could mean the average water level upstream of the culvert to be higher that in reality and downstream average water level will be lower.
	* Multiply default SX boundary storage with the 'a' attribute.		* Multiply default SX boundary storage with the 'a' attribute.
	* Use polygon SX for more stability, see further guidance <u>[[~~TUFLOW_1D2D_SX_Advice~~ \| here]]</u>. If using shapefiles, 2d_bc SX polygon should be read into TUFLOW on the same line as 2d_bc CN line separated by a vertical bar.		* Use polygon SX for more stability, see further guidance <u>[[TUFLOW_1D2D_Boundary_Configuration_Guidance \| here]]</u>. If using shapefiles, 2d_bc SX polygon should be read into TUFLOW on the same line as 2d_bc CN line separated by a vertical bar.
	* Use Sub-Grid Sampling (SGS) to improve volume calculations upstream and downstream of the structure.		* Use Sub-Grid Sampling (SGS) to improve volume calculations upstream and downstream of the structure.

Pavlina Monhartova: /* Notes for all features */

2025-06-17T08:13:28Z

Notes for all features

← Older revision		Revision as of 18:13, 17 June 2025
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	=== Notes for all features===		=== Notes for all features===
	* Use the latest available TUFLOW release.		* Use the latest available TUFLOW release.
	* Use Sub-Grid Sampling (SGS) if using HPC. This allows for more accurate calculations of flow and water level that transitions into the 1D features ~~trough~~ the 1D/2D links.		* Use Sub-Grid Sampling (SGS) if using HPC. This allows for more accurate calculations of flow and water level that transitions into the 1D features through the 1D/2D links.
	* Double precision might be used, however this would cause models running slower and other measures are recommended to try first.		* Double precision might be used, however this would cause models running slower and other measures are recommended to try first.
	* Lower 1D timestep can be sensitivity tested, however the timestep should still remain within reasonable bounds. If the 1D timestep is required to be very small for stability reasons, usually other measures can be taken to improve the stability and consequently run time of the model.		* Lower 1D timestep can be sensitivity tested, however the timestep should still remain within reasonable bounds. If the 1D timestep is required to be very small for stability reasons, usually other measures can be taken to improve the stability and consequently run time of the model.

Pavlina Monhartova: /* Notes for all features */

2025-06-17T08:12:13Z

Notes for all features

← Older revision		Revision as of 18:12, 17 June 2025
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	* Double precision might be used, however this would cause models running slower and other measures are recommended to try first.		* Double precision might be used, however this would cause models running slower and other measures are recommended to try first.
	* Lower 1D timestep can be sensitivity tested, however the timestep should still remain within reasonable bounds. If the 1D timestep is required to be very small for stability reasons, usually other measures can be taken to improve the stability and consequently run time of the model.		* Lower 1D timestep can be sensitivity tested, however the timestep should still remain within reasonable bounds. If the 1D timestep is required to be very small for stability reasons, usually other measures can be taken to improve the stability and consequently run time of the model.
	* If using TUFLOW Classic, 2D timestep should be between 1/5 and 1/2 of the cell size in metres. Lowering within this range might be beneficial for stabilising 1d/2D links.		* If using TUFLOW Classic, 2D timestep should be between 1/5 and 1/2 of the cell size in metres. Lowering 2D timestep within this range might be beneficial for stabilising 1D/2D links.

	== My model reports very high mass balance error at the beginning, then it lowers. Is it unhealthy? ==		== My model reports very high mass balance error at the beginning, then it lowers. Is it unhealthy? ==

Pavlina Monhartova: /* Notes for all features */

2025-06-17T08:11:40Z

Notes for all features

← Older revision		Revision as of 18:11, 17 June 2025
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	* Double precision might be used, however this would cause models running slower and other measures are recommended to try first.		* Double precision might be used, however this would cause models running slower and other measures are recommended to try first.
	* Lower 1D timestep can be sensitivity tested, however the timestep should still remain within reasonable bounds. If the 1D timestep is required to be very small for stability reasons, usually other measures can be taken to improve the stability and consequently run time of the model.		* Lower 1D timestep can be sensitivity tested, however the timestep should still remain within reasonable bounds. If the 1D timestep is required to be very small for stability reasons, usually other measures can be taken to improve the stability and consequently run time of the model.
			* If using TUFLOW Classic, 2D timestep should be between 1/5 and 1/2 of the cell size in metres. Lowering within this range might be beneficial for stabilising 1d/2D links.

	== My model reports very high mass balance error at the beginning, then it lowers. Is it unhealthy? ==		== My model reports very high mass balance error at the beginning, then it lowers. Is it unhealthy? ==

Pavlina Monhartova: /* How can I stabilise 1D features? */

2024-10-14T08:56:47Z

How can I stabilise 1D features?

← Older revision		Revision as of 18:56, 14 October 2024
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	** Set an initial water level so the model doesn't start completely dry. This can be done globally with <font color="blue"><tt>Set IWL </tt></font> command or locally with 2d_iwl polygon.		** Set an initial water level so the model doesn't start completely dry. This can be done globally with <font color="blue"><tt>Set IWL </tt></font> command or locally with 2d_iwl polygon.

	==How can I stabilise 1D features?==		==How can I stabilise 1D features and their 1D/2D boundaries?==
	=== 1D open channels including connected bridges and culverts ===		=== 1D open channels including connected bridges and culverts ===
	* Split or merge open channel sections - the general advice is to have the length of open channels about 3 to 5 times of their width. Merging very short channels will provide sufficient storage. Splitting long channels into shorter ones with more 1D nodes might smooth the water level slope and the simulated flow rate can become more stable.		* Split or merge open channel sections - the general advice is to have the length of open channels about 3 to 5 times of their width. Merging very short channels will provide sufficient storage. Splitting long channels into shorter ones with more 1D nodes might smooth the water level slope and the simulated flow rate can become more stable.

ElizaCollison: /* How can I stabilise 2D boundary? */

2023-06-14T12:28:36Z

How can I stabilise 2D boundary?

← Older revision		Revision as of 22:28, 14 June 2023
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	** The new cell size insensitive Wu turbulence scheme in TUFLOW HPC has become the default from 2020 release. The previous default, Smagorinsky viscosity formulation, could produce unrealistic eddies in the model when cell size got smaller than flow depth.		** The new cell size insensitive Wu turbulence scheme in TUFLOW HPC has become the default from 2020 release. The previous default, Smagorinsky viscosity formulation, could produce unrealistic eddies in the model when cell size got smaller than flow depth.
	** Since the 2020 release all H boundaries including QT boundary adjusts the water level by the dynamic head when water is entering the model (a common approach in CFD modelling), which reduces the chance of spurious circulations caused by the boundary assumptions and/or schematisation of the boundary.		** Since the 2020 release all H boundaries including QT boundary adjusts the water level by the dynamic head when water is entering the model (a common approach in CFD modelling), which reduces the chance of spurious circulations caused by the boundary assumptions and/or schematisation of the boundary.
			* External boundaries (e.g. HT, HQ, QT) should be snapped to the code layer.
	* Boundaries should be digitised perpendicular to the flow and well away from the area of interest.		* Boundaries should be digitised perpendicular to the flow and well away from the area of interest.
	* Every flow path should have its own boundary.		* Every flow path should have its own boundary.

Pavlina Monhartova: /* 1D open channels */

2022-11-03T00:53:27Z

1D open channels

← Older revision		Revision as of 10:53, 3 November 2022
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	==How can I stabilise 1D features?==		==How can I stabilise 1D features?==
	=== 1D open channels ===		=== 1D open channels including connected bridges and culverts ===
	* Split or merge open channel sections - the general advice is to have the length of open channels about 3 to 5 times of their width. Merging very short channels will provide sufficient storage. Splitting long channels into shorter ones with more 1D nodes might smooth the water level slope and the simulated flow rate can become more stable.		* Split or merge open channel sections - the general advice is to have the length of open channels about 3 to 5 times of their width. Merging very short channels will provide sufficient storage. Splitting long channels into shorter ones with more 1D nodes might smooth the water level slope and the simulated flow rate can become more stable.
	* Increase the storage area where required with 1d_na table or 1d_nwk ANA attribute with type NODE. The extra storage can cause a lag in a the hydrograph and sensitivity testing should be undertaken.		* Increase the storage area where required with 1d_na table or 1d_nwk ANA attribute with type NODE. The extra storage can cause a lag in a the hydrograph and sensitivity testing should be undertaken.

Pavlina Monhartova: /* Notes for all features */

2022-07-07T01:56:52Z

Notes for all features

← Older revision		Revision as of 11:56, 7 July 2022
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	=== Notes for all features===		=== Notes for all features===
	* Use the latest available TUFLOW release.		* Use the latest available TUFLOW release.
			* Use Sub-Grid Sampling (SGS) if using HPC. This allows for more accurate calculations of flow and water level that transitions into the 1D features trough the 1D/2D links.
	* Double precision might be used, however this would cause models running slower and other measures are recommended to try first.		* Double precision might be used, however this would cause models running slower and other measures are recommended to try first.
	* Lower 1D timestep can be sensitivity tested, however the timestep should still remain within reasonable bounds. If the 1D timestep is required to be very small for stability reasons, usually other measures can be taken to improve the stability and consequently run time of the model.		* Lower 1D timestep can be sensitivity tested, however the timestep should still remain within reasonable bounds. If the 1D timestep is required to be very small for stability reasons, usually other measures can be taken to improve the stability and consequently run time of the model.

Pavlina Monhartova: /* Notes for all */

2022-07-07T01:54:24Z

Notes for all

← Older revision		Revision as of 11:54, 7 July 2022
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	* Check that a sufficient number of SX cells are selected for the magnitude of the inflows. If it’s a relatively small 2D cell size and a large pit inflow (negative flow) or surcharge (positive flow) is applied to too few SX cells this will may cause instabilities (which is why TUFLOW selects more than one cell at a pit SX if the width of the pit exceeds the 2D cell size). Increasing the number of SX cells may help.		* Check that a sufficient number of SX cells are selected for the magnitude of the inflows. If it’s a relatively small 2D cell size and a large pit inflow (negative flow) or surcharge (positive flow) is applied to too few SX cells this will may cause instabilities (which is why TUFLOW selects more than one cell at a pit SX if the width of the pit exceeds the 2D cell size). Increasing the number of SX cells may help.

	=== Notes for all ===		=== Notes for all features===
	* Use the latest available TUFLOW release.		* Use the latest available TUFLOW release.
	* Double precision might be used, however this would cause models running slower and other measures are recommended to try first.		* Double precision might be used, however this would cause models running slower and other measures are recommended to try first.

Pavlina Monhartova: /* Notes for all */

2022-06-28T06:05:57Z

Notes for all

← Older revision		Revision as of 16:05, 28 June 2022
Line 47:		Line 47:

	=== Notes for all ===		=== Notes for all ===
			* Use the latest available TUFLOW release.
	* Double precision might be used, however this would cause models running slower and other measures are recommended to try first.		* Double precision might be used, however this would cause models running slower and other measures are recommended to try first.
	* Lower 1D timestep can be sensitivity tested, however the timestep should still remain within reasonable bounds. If the 1D timestep is required to be very small for stability reasons, usually other measures can be taken to improve the stability and consequently run time of the model.		* Lower 1D timestep can be sensitivity tested, however the timestep should still remain within reasonable bounds. If the 1D timestep is required to be very small for stability reasons, usually other measures can be taken to improve the stability and consequently run time of the model.