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Integrated BIM tools, including Revit, AutoCAD, and Civil 3D
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Professional CAD/CAM tools built on Inventor and AutoCAD
Integrated BIM tools, including Revit, AutoCAD, and Civil 3D
Professional CAD/CAM tools built on Inventor and AutoCAD
Transcript
00:03
When combining 1D and 2D river models, the exchange of flow between the 1D and 2D systems can only take place at specific objects.
00:15
It is therefore important to understand the methodology for the different approaches,
00:20
so that you can get the flow exchange represented accurately within your models.
00:25
These could be two separate existing models, or you may be building a new integrated model.
00:31
The mechanism would be the same in both cases, but it is always easier to plan out aspects with a new model build.
00:39
Coupling can take place in two ways.
00:42
The link between 2D elements and 1D nodes is made up of point connections.
00:48
The link between 2D elements and 1D river reaches is made up of lateral bank connections.
00:56
By default, flow is exchanged between the engines at the major timesteps.
01:02
Where you have large flows, complex interactions, or generally want this interaction to be as accurate as possible,
01:09
you need to reduce the simulation timestep to be more appropriate.
01:14
Typically for a 1D-2D model, your simulation timestep should be between 1 and 5 seconds.
01:22
To get the exchange of flow to be an accurate representation,
01:26
you need to select an approach that is appropriate for the mechanism and scale of the model.
01:32
Point coupling takes place between a single element and a node object.
01:37
Typical uses are in locations where manholes, gullies, or outfalls exist.
01:43
Where you have structures that far exceed a single face length,
01:47
you need to employ the linear coupling approach, so that the flow is exchanged across multiple elements.
01:54
This methodology is less flexible, as you only have the irregular weir linkage.
02:00
Typical usage is along river banks and at river ends.
02:05
Linear coupling can occur at either river reach banks or inline bank links, both of which are built from bank line data.
02:14
An inline bank allows coupling in the direction of flow.
02:18
When you link a 1D and 2D model,
02:21
you may need to consider the starting condition of your simulation in more detail,
02:26
and how you align levels in the 1D and 2D domains.
02:31
Only the 1D model undertakes initialization,
02:35
so you need to set the starting conditions within the 2D model via the initial conditions 2D object
02:43
—which can be used to assign hydraulic, infiltration, and water quality conditions to mesh elements at the start of a 2D simulation.
02:52
You can use one initial conditions 2D object per run setup.
03:03
They can be imported or generated manually.
03:06
The initial conditions themselves are defined in an initial conditions 2D object.
03:12
Values defined in the initial conditions 2D object supersede the values from an initial state simulation.
03:21
Aligning the 1D and 2D levels at the start of a simulation is unlikely to be a simple process in larger or more complex 1D-2D models.
03:32
If using the initial conditions 2D objects to set all of these conditions is too time-consuming,
03:39
you may want to use an initial state file in place of initialization, which represents both the 1D and 2D in a steady state.
03:49
If you have extreme starting conditions, creating the state file can be slightly more involved,
03:55
as it likely requires starting the initial state simulation at a low or dry condition and then increasing the flows over a reasonable period.
Video transcript
00:03
When combining 1D and 2D river models, the exchange of flow between the 1D and 2D systems can only take place at specific objects.
00:15
It is therefore important to understand the methodology for the different approaches,
00:20
so that you can get the flow exchange represented accurately within your models.
00:25
These could be two separate existing models, or you may be building a new integrated model.
00:31
The mechanism would be the same in both cases, but it is always easier to plan out aspects with a new model build.
00:39
Coupling can take place in two ways.
00:42
The link between 2D elements and 1D nodes is made up of point connections.
00:48
The link between 2D elements and 1D river reaches is made up of lateral bank connections.
00:56
By default, flow is exchanged between the engines at the major timesteps.
01:02
Where you have large flows, complex interactions, or generally want this interaction to be as accurate as possible,
01:09
you need to reduce the simulation timestep to be more appropriate.
01:14
Typically for a 1D-2D model, your simulation timestep should be between 1 and 5 seconds.
01:22
To get the exchange of flow to be an accurate representation,
01:26
you need to select an approach that is appropriate for the mechanism and scale of the model.
01:32
Point coupling takes place between a single element and a node object.
01:37
Typical uses are in locations where manholes, gullies, or outfalls exist.
01:43
Where you have structures that far exceed a single face length,
01:47
you need to employ the linear coupling approach, so that the flow is exchanged across multiple elements.
01:54
This methodology is less flexible, as you only have the irregular weir linkage.
02:00
Typical usage is along river banks and at river ends.
02:05
Linear coupling can occur at either river reach banks or inline bank links, both of which are built from bank line data.
02:14
An inline bank allows coupling in the direction of flow.
02:18
When you link a 1D and 2D model,
02:21
you may need to consider the starting condition of your simulation in more detail,
02:26
and how you align levels in the 1D and 2D domains.
02:31
Only the 1D model undertakes initialization,
02:35
so you need to set the starting conditions within the 2D model via the initial conditions 2D object
02:43
—which can be used to assign hydraulic, infiltration, and water quality conditions to mesh elements at the start of a 2D simulation.
02:52
You can use one initial conditions 2D object per run setup.
03:03
They can be imported or generated manually.
03:06
The initial conditions themselves are defined in an initial conditions 2D object.
03:12
Values defined in the initial conditions 2D object supersede the values from an initial state simulation.
03:21
Aligning the 1D and 2D levels at the start of a simulation is unlikely to be a simple process in larger or more complex 1D-2D models.
03:32
If using the initial conditions 2D objects to set all of these conditions is too time-consuming,
03:39
you may want to use an initial state file in place of initialization, which represents both the 1D and 2D in a steady state.
03:49
If you have extreme starting conditions, creating the state file can be slightly more involved,
03:55
as it likely requires starting the initial state simulation at a low or dry condition and then increasing the flows over a reasonable period.
When combining 1D and 2D river models, exchange of flow between 1D and 2D systems can only take place at specific objects.
Important to understand methodology for different approaches, to accurately represent flow exchange within models.
Could be two separate existing models, or you may be building new integrated model—same mechanism, but easier to plan with new model build.
Can take place in two ways:
By default, flow exchanged between engines at major timesteps.
In the case of large flows, complex interactions, or need for accuracy, reduce simulation timestep to be more appropriate.
Typical simulation timestep for 1D-2D model is between 1 and 5 seconds.
To accurately represent exchange of flow, need to select approach appropriate for mechanism and scale of model.
Between single element and node object.
Typically used in locations with manholes, gullies, or outfalls.
Where structures far exceed single face length, employ linear coupling approach, so flow is exchanged across multiple elements.
Less flexible methodology—only have irregular weir linkage.
Typically used along river banks and at river ends.
Linear coupling can occur at either river reach banks or inline bank links—both built from bank line data.
Inline bank allows coupling in direction of flow.
When linking 1D and 2D model, may need to consider starting condition of simulation in detail, and how levels are aligned in 1D and 2D domains.
Only 1D model undertakes initialization, so need to set starting conditions within 2D model via initial conditions 2D object—can be used to assign hydraulic, infiltration, and water quality conditions to mesh elements at start of 2D simulation.
Can use one initial conditions 2D object per run setup.
Used as part of mesh generation.
Can be imported or generated manually.
Initial conditions are defined in initial conditions 2D object.
Values defined in initial conditions 2D object supersede values from initial state simulation.
Aligning 1D and 2D levels at start of simulation unlikely to be simple process in large or complex 1D-2D models.
If using initial conditions 2D objects to set all conditions is too time-consuming, can use initial state file in place of initialization, which represents both 1D and 2D in steady state.
With extreme starting conditions, creating state file can be more involved— likely requires starting initial state simulation at low or dry condition, and then increasing flows over reasonable period.
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