About modelling 2D objects

2D Objects:

Specific to 2D domain and used to bring flow to 2D mesh or represent structures, such as culverts and bridges.

Calculations for 2D objects maintained within 2D engine.

2D Calculations:

Can be computationally expensive, so reducing ensures best user experience.

ICM offers flexibility for generating flows, either externally through event files, or internally using direct rainfall or subcatchments.

Disadvantage of Inflow events is having to set up simulations individually.

More streamlined network approach is to model upstream rural catchments using large subcatchments, which discharge into point or line sources at upstream extent of meshes.

• Can significantly cut down size of 2D zone.
• Can still use rainfall events to trigger simulations

2D Point/Line Source Objects:

2D Point Source:

• Used to define location of flow-time boundary point within 2D zone.
• Associated inflow discharges to 2D mesh element in which point is located.

2D Line Source:

• Similar to 2D point source objects.
• Used to define the location of a flow-time boundary line within a 2D zone.
• Associated inflow discharges into 2D mesh elements adjacent to line.

2D Conduits:

Can be used in 2D simulation to introduce unidimensional hydraulic structures directly in 2D engine.

Allow transfer of flow between two areas of 2D zone.

Intended to represent a drainage structure, such as a culvert beneath a road. This allows you to maintain road deck in mesh, but represent flow through culvert underneath.

When connected to a Connect 2D node, flow calculation depends on connection type:

• Closed - No flow through edge—for example, at upstream edge of 2D conduit.
• Lost - Any flow through edge is lost. 2D engine assumes uniform flow conditions at edge.
• 2D - Indicates connection to element in 2D surface. Hydraulic variables in 2D element used as boundary condition in 2D conduit.
• Break - Used to connect two 2D conduits. Flow calculated as if two 2D conduits are joined and assumes the break type of Connect 2D node does not have storage.

Linear Drainage (2D):

Type of 2D conduit that represents linear gully, such as a slot drain connected vertically to a 2D surface.

1D-2D linear connection that can be used where drain slot or trench is much longer than equivalent face length of 2D element area defined on 2D zones.

Used on roads and large infrastructures, such as airports.

Can also be used for detailed drainage site projects, where 2D modelling resolution is 100m2 or less.

Base Linear Structure (2D):

Line objects used as part of 2D mesh generation process.

Represent structures, such as a wall with specified porosity and height, used in 2D simulation process.

Structure types that can be modelled:

• Walls
• Weirs—thin plate weir or broad crested weir
• User-controlled, with flow through structure controlled by user-defined head-discharge curve

Sluices and bridges along the length of the linear structure can be modelled by associating Sluice Linear Structure (2D) and Bridge Linear Structure (2D) objects with the base linear structure.

Sluice Linear Structure (2D):

Used to define sluice gate dimensions, coefficients, and location of sluices within 2D base linear structures.

Can be created in Lines Grid or digitized directly on GeoPlan as line objects.

Assume geometry length of referenced 2D base linear structure, so digitizing not necessary.

Bridge Linear Structure (2D):

Used to define bridge dimensions, coefficients, and location of bridges within 2D base linear structures.

Appears as a line and does not conceptualize bridge depth, so there is reluctance to use it.

May only become hydraulically unrepresentative with bridge depth significantly greater than distance between element centroids. In this case, can be modelled as conduit (2D) link instead.

Time-varying Geometry:

Geometry of objects interacting with 2D domain can be adjusted.

Most likely used to represent collapse or breach.

Can define time-varying level for:

• River reaches—left and right bank
• Inline banks—used as 1D-2D link
• Base linear structures (2D)

Breach can be modelled using Real Time Control (RTC) definitions to specify vertical movement of bank/linear structure point vertices with respect to time.

At each run timestep, ICM evaluates RTC definitions and uses them to set current elevation of any points with RTC definition specified.