Base Linear Structure (2D) Data Fields

Base Linear Structure (2D) data can be edited on either the BaseLinear Structure (2D) Grid Window of the Lines Grid or the Base Linear Structure (2D) Property Sheet.

Most data can be edited on the grid, but some fields cannot be displayed in the grid format.

To view and edit all base linear structure (2D) data, use the Property Sheet.

The following describes all the data which can be used to define a Base Linear Structure (2D) object.

Common Data Fields

Fields that are common to the majority of objects can be found in the Common Fields topic.

Base Linear Structure (2D) Data

Database Table Name: hw_2d_linear_structure

Show Columns

Database Names

Size, Type and Units

Defaults and Error Limits

Field Name

Help Text

Database Field

Data Type

Size

Units

Precision

Default

Error Lower Limit

Error Upper Limit

Warning Lower Limit

Warning Upper Limit

ID

ID of the line.

line_id

Text

64

 

0

 

0

0

0

0

Asset ID

For reference only. Designed as a reference to an asset database, but could be used for anything.

asset_id

Text

64

 

0

 

 

 

 

 

Structure type

Type of structure:

Database Value

Description

Help Text
Wall Wall Line represents a wall.
Weir Weir Line represents a weir
User control User control Flow across the wall is controlled by a head-unit flow relationship defined by the Head Unit Flow specified in the Head unit flow table field.

structure_type

Text

20

 

0

Porous wall

0

0

0

0
Weir type

Enabled if Structure type is set to Weir.

Type of weir:

Database Value

Description

Help Text
Broad crested Broad crested Round nosed broad crested weir
Thin plate Thin plate Standard, thin plate weir
weir_type Text 15   0 Thin plate        
Discharge coefficient

Enabled if Structure type is set to Weir and Weir type is set to Thin plate.

The coefficient for the weir flow equations. The default value of 0.85 corresponds to a weir of width equal to that of the approach channel. Values typically range between 0.2 and 3.0.

 discharge Double     3 0.85 0 0.01    
Horizontal section length

Enabled if Structure type is set to Weir and Weir type is set to Broad crested.

Width of weir crest.

 horiz_sect_length Double   L 3     0    
Head unit flow table Enabled if Structure type is set to User control

Name of the Head Unit Flow defining the relationship between head difference and unit flow through the structure; where head difference is the difference between upstream water level and either downstream water level or crest level, whichever is higher.

 head_unit_discharge_id Text 64   0          

Crest level

Type of wall:

Database Value

Description

Help Text

Infinite

Infinite

Structure is considered to be an infinitely high barrier (available when Structure type is set to Wall only).

Height

Height

The height of the structure (above ground level) is specified in the Height field.

Level

Level

The level of the structure (above datum) is specified in the Level field
Irregular Irregular The crest level of the structure is specified in the Section data editor

crest_level

Text

20

 

0

Irregular

0

0

0

0

Height

Enabled if Crest Level of type Height is selected.

Height of the top of the structure from ground level.

For each segment of structure, this is the height above the highest of the ground levels of the two computational elements either side of the structure.

Note that when a 2D Sluice is associated with the base structure, the crest level height of the base structure will be overridden by the level of the top of the sluice gate along the length of the sluice.

height

Double

 

Y

3

0.0

0

 

 

 

Level

Enabled if Crest Level of type Level is selected.

Height above datum of the top of the structure.

Note that when a 2D Sluice is associated with the base structure, the crest level height of the base structure will be overridden by the level of the top of the sluice gate along the length of the sluice.

level

Double

 

Z

3

0.0

 

 

 

 

Remove wall during simulation

Enabled when Structure type is set to Wall.

Collapse option for wall:

Database Value

Description

Help Text

Never

Never

Wall never collapses.

Fully

Fully

The entire length of the wall collapses when the wall removal threshold is met in any of the mesh elements adjacent to the wall.

Partially

Partially

When the wall removal threshold is met in a mesh element adjacent to the wall, the length of the wall adjacent to the mesh element collapses.

remove_wall

Text

10

 

0

Never

 

 

 

 

Wall removal trigger

Enabled when Structure type is set to Wall and Wall removal trigger is Fully or Partially.

Variable used to determine when wall is collapsed. This trigger variable relates to the 2D results in the mesh elements adjacent to the wall face.

Database Value

Description

Help Text

Depth

Depth

Depth of water in mesh elements adjacent to wall.

Elevation

Elevation

Water surface elevation of mesh elements adjacent to the wall.

Velocity

Velocity

Velocity in mesh elements adjacent to the wall, in the normal direction to the wall.

Unit flow

Unit flow

Flow per unit of length in mesh elements adjacent to wall, in the normal direction to the wall.

Total head

Total head

Total head in the normal direction to the wall, in adjacent elements to the wall multiplied by the Hydrostatic pressure coefficient. Total head is calculated as:

V = A x H

Where:

H = h + u2/(2g)

V(m): Corrected head

A: Hydrostatic pressure coefficient

H(m): total head

h(m): depth

u(m/s): normal velocity to the wall

g(m/s2): gravity

Force per unit length

Force per unit length

Total force per unit length in the normal direction to the wall, in adjacent elements to the wall. Force per unit length is calculated as:

F = A x 0.5 x ρgH2

Where:

F(kN/m): Force per unit length

A: Hydrostatic pressure coefficient

H(m): total head

ρ (Tm/m3): water density

g(m/s2): gravity

wall_removal_trigger

Text

21

 

0

Depth

 

 

 

 

Use difference across wall

Enabled when Structure type is set to Wall and Wall removal trigger is Fully or Partially.

Check this option to determine when the wall collapses by calculating the difference in the Wall removal trigger variable between the two elements on either side of the wall.

If this option is not checked, wall collapse will be determined by value of trigger variable in any of the mesh elements adjacent to the wall.

use_diff_across_wall

Boolean

 

 

0

0

 

 

 

 

Depth threshold

Enabled when Wall removal trigger is set to Depth.

  • When the Use difference across wall option is not selected: the wall is collapsed if the depth of water in any of the mesh elements adjacent to the wall exceeds the Depth threshold.

  • When the Use difference across wall option is selected: the wall is collapsed when the difference between the water depths of the two elements adjacent to the wall exceeds the Depth threshold.

depth_threshold

Double

 

Y

3

0.0

 

 

 

 

Elevation threshold

Enabled when Wall removal trigger is set to Elevation.

  • When the Use difference across wall option is not selected: the wall is collapsed if the water surface elevation in any of the mesh elements adjacent to the wall exceeds the Elevation threshold.

  • When the Use difference across wall option is selected: the wall is collapsed when the difference between the water surface elevation of the two elements adjacent to the wall exceeds the Elevation threshold.

This only applies if at least one of the adjacent elements is wet.

elevation_threshold

Double

 

Z

3

0.0

 

 

 

 

Velocity threshold

Enabled when Wall removal trigger is set to Velocity.

  • When the Use difference across wall option is not selected: the wall is collapsed if the normal velocity to the wall in any of the mesh elements adjacent to the wall exceeds the Velocity threshold.

  • When the Use difference across wall option is selected: the wall is collapsed when the difference between the velocity normal to the wall of the two elements adjacent to the wall exceeds the Velocity threshold.

velocity_threshold

Double

 

V

3

0.0

 

 

 

 

Unit flow threshold

Enabled when Wall removal trigger is set to Unit flow.

  • When the Use difference across wall option is not selected: the wall is collapsed if the flow per unit length normal to the wall in any of the mesh elements adjacent to the wall exceeds the Unit flow threshold.

  • When the Use difference across wall option is selected: the wall is collapsed when the difference between the flow per unit length normal to the wall of the two elements adjacent to the wall exceeds the Unit flow threshold.

unit_flow_threshold

Double

 

UQ

3

0.0

 

 

 

 

Total head threshold

Enabled when Wall removal trigger is set to Total head.

  • When the Use difference across wall option is not selected: the wall is collapsed if the corrected total head in the normal direction to the wall in any of the mesh elements adjacent to the wall exceeds the Total head threshold.

  • When the Use difference across wall option is selected: the wall is collapsed when the difference between the corrected total head normal to the wall of the two elements adjacent to the wall exceeds the Total head threshold.

Corrected total head is calculated by the following equation:

V = A x H

Where:

H = h + u2/(2g)

V(m): Corrected head

A: Hydrostatic pressure coefficient

H(m): total head

h(m): depth

u(m/s): normal velocity to the wall

g(m/s2): gravity

total_head_threshold

Double

 

Y

3

0.0

 

 

 

 

Force threshold

Enabled when Wall removal trigger is set to Force per unit length.

  • When the Use difference across wall option is not selected: the wall is collapsed if the force per unit length in the normal direction to the wall in any of the mesh elements adjacent to the wall exceeds the Force threshold.

  • When the Use difference across wall option is selected: the wall is collapsed when the difference between the force per unit length normal to the wall of the two elements adjacent to the wall exceeds the Force threshold.

Force per unit length is calculated as:

F = A x 0.5 x ρgH2

Where:

F(kN/m): Force per unit length

A: Hydrostatic pressure coefficient

H(m): total head

ρ(Tm/m3): water density

g(m/s2): gravity

force_threshold

Double

 

UF

3

0.0

 

 

 

 

Hydrostatic pressure coefficient

Multiplying factor applied when using Total head or Force per unit length as the Wall removal trigger.

hydro_press_coeff

Double

 

 

3

1.0

 

 

 

 

Porosity

Enabled when Structure type is set to Wall.

Porosity factor between 0 and 1, where 0 represents impermeable and 1 represents fully permeable.

See Linear Structures (2D) for further information.

porosity

Double

 

 

3

0.0

0

1

 

 
Blockage

Enabled when Structure type is set to Weir or User control.

Blockage factor between 0 and 1, where 0 represents no blockage and 1 represents fully blocked (no flow can pass over the weir).

See Linear Structures (2D) for further information.

 blockage Double     3 0.0 0 1    
Headloss specification

Indicates how the headloss coefficient is to be specified. This can be set to:

  • Uniform - one Headloss coefficient is specified which is applied to both the upstream and downstream elements.
  • Upstream & downstream - separate headloss coefficients, US headloss coefficient and DS headloss coefficient, are specified which are applied to the upstream and downstream elements respectively.

See Base Linear Structures (2D) for further information.

 headloss_spec Text 25   0 Uniform 0 0 0 0
Headloss coefficient type

Indicates the type of headloss coefficient to be used. This can be set to:

  • Fixed - the headloss slope across the structure is scaled by the inverse of the distance between element baricentres. Therefore the resulting headloss across the structure is practically independent of the mesh size.
  • Per unit length - the headloss is calculated per unit length and hence it is mesh dependent.

See Base Linear Structures (2D) for further information.

 headloss_type Text 20   0 Fixed 0 0 0 0
Unit headloss coefficient

Enabled when Headloss specification is either not set or set to Uniform, and Headloss coefficient type is either not set or set to Per unit length.

Head loss coefficient per unit length that applies to the adjacent elements of the line structure.

See Base Linear Structures (2D) for further information.

 headloss_coeff Double   UHC 3 0.0 0      
US unit headloss coefficient

Enabled when Headloss specification is set to Upstream & downstream, and Headloss coefficient type is either not set or set to Per unit length.

Headloss coefficient per unit length that applies to the upstream element of the line structure.

See Base Linear Structures (2D) for further information.

 us_unit_headloss_coeff Double   UHC 3 0.0 0      
DS unit headloss coefficient

Enabled when Headloss specification is set to Upstream & downstream, and Headloss coefficient type is either not set or set to Per unit length.

Headloss coefficient per unit length that applies to the downstream element of the line structure.

See Base Linear Structures (2D) for further information.

 ds_unit_headloss_coeff Double   UHC 3 0.0 0      
Headloss coefficient

Enabled when Headloss specification is either not set or set to Uniform, and Headloss coefficient type is set to Fixed.

Head loss coefficient that applies to the adjacent elements of the line structure.

See Base Linear Structures (2D) for further information.

 headloss_coeff2 Double     3 0.0 0      
US headloss coefficient

Enabled when Headloss specification is set to Upstream & downstream, and Headloss coefficient type is set to Fixed.

Headloss coefficient that applies to the upstream element of the line structure.

See Base Linear Structures (2D) for further information.

 us_headloss_coeff Double     3 0.0 0      
DS headloss coefficient

Enabled when Headloss specification is set to Upstream & downstream, and Headloss coefficient type is set to Fixed.

Headloss coefficient that applies to the downstream element of the line structure.

See Base Linear Structures (2D) for further information.

 ds_headloss_coeff Double     3 0.0 0      
Lateral friction coefficient

Coefficient of energy loss caused by the friction of the flow against the line structure in the tangential direction.

See Linear Structures (2D) for further information.

 lateral_friction Double     4 0.0        
No reverse flow

Check this option to define the structure as unidirectional - flow is only allowed to flow from the structure's upstream side to its downstream side; no reverse flow is allowed.

If this option is unchecked, the structure is taken to be bidirectional and flow will be allowed in both directions.

 use_direction Boolean     0 0        

Section data

Database Table Name: hw_2d_struct_sec

Show Columns

Database Names

Size, Type and Units

Defaults and Error Limits

Position in Data Structure

Field Name

Help Text

Database Field

Data Type

Size

Units

Default

Error Lower Limit

Error Upper Limit

Warning Lower Limit

Warning Upper Limit
1 X Coordinate X coordinate of section vertex X Double   L        

 
2 Y Coordinate Y coordinate of section vertex Y Double   L        

 
3 Crest level Elevation of section vertex Z Double   Z   -9999 9999  

6000
4 RTC Definition Name of the RTC Table or Variable that defines vertical movement of the vertex. Used to model breaching of the structure. rtc_definition Text 10            

sections

Array

 

 

0

 

0

0

0

0

Length

Length of the Line.

length

Single

 

L

3

 

 

 

 

 

Base Linear Structure (2D)

Lines

Lines Grid

Property Sheets