Adding porous walls and polygons

00:03

It is often necessary to edit a mesh using various objects to provide more detail

00:09

and improve the representation of the underlying topography.

00:14

These mesh editing objects can be manually added or taken from external files,

00:20

layers displayed in the GeoPlan view, or objects within the network.

00:25

Porous walls and polygons represent walls with a specified porosity and height that are used during the 2D simulation process.

00:36

A porous wall collinear with the boundary of a 2D zone overrides the boundary condition.

00:43

It is possible to set parameters for the porous wall object that results in the full or partial removal of the wall during a simulation.

00:52

This example has a selection of porous walls and porous polygons that have varying properties.

01:00

Open the Properties window of a porous polygon to view or change its settings.

01:06

The Porosity must be a value between 0 and 1, where 0 is impermeable and 1 is fully porous, meaning it has no impact on the flow.

01:20

As an example, a low porosity in the range of 0.05 - 0.2 may be used to represent a building.

01:29

There are three Crest level options:

01:33

Infinite, Height, and Level.

01:36

This is the point up to which the porosity applies—above this, there will be no effect.

01:43

You can also choose to Remove wall during simulation with three options:

01:49

Never, Fully, or Partially.

01:53

For the Partially option, only faces of the wall meeting the criteria are removed.

01:59

This option can be used to simulate wall collapse.

02:04

The final option, only available for a porous polygon, applies No rainfall within the polygon when selected.

02:13

To best demonstrate the effect of these objects, in this example, a simulation is run with the porous walls and polygons included.

02:22

As the water passes through the objects, you can see the porosity taking effect.

02:28

Those with lower porosity have a higher depth building up behind them and are the first to be removed when the height threshold is reached.

Video transcript

00:03

It is often necessary to edit a mesh using various objects to provide more detail

00:09

and improve the representation of the underlying topography.

00:14

These mesh editing objects can be manually added or taken from external files,

00:20

layers displayed in the GeoPlan view, or objects within the network.

00:25

Porous walls and polygons represent walls with a specified porosity and height that are used during the 2D simulation process.

00:36

A porous wall collinear with the boundary of a 2D zone overrides the boundary condition.

00:43

It is possible to set parameters for the porous wall object that results in the full or partial removal of the wall during a simulation.

00:52

This example has a selection of porous walls and porous polygons that have varying properties.

01:00

Open the Properties window of a porous polygon to view or change its settings.

01:06

The Porosity must be a value between 0 and 1, where 0 is impermeable and 1 is fully porous, meaning it has no impact on the flow.

01:20

As an example, a low porosity in the range of 0.05 - 0.2 may be used to represent a building.

01:29

There are three Crest level options:

01:33

Infinite, Height, and Level.

01:36

This is the point up to which the porosity applies—above this, there will be no effect.

01:43

You can also choose to Remove wall during simulation with three options:

01:49

Never, Fully, or Partially.

01:53

For the Partially option, only faces of the wall meeting the criteria are removed.

01:59

This option can be used to simulate wall collapse.

02:04

The final option, only available for a porous polygon, applies No rainfall within the polygon when selected.

02:13

To best demonstrate the effect of these objects, in this example, a simulation is run with the porous walls and polygons included.

02:22

As the water passes through the objects, you can see the porosity taking effect.

02:28

Those with lower porosity have a higher depth building up behind them and are the first to be removed when the height threshold is reached.

Video quiz

Required for course completion

When editing a 2D mesh, what happens when you place a porous wall collinear with the boundary of a 2D zone?

(Select one)
Select an answer

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Step-by-step guide

Porous walls and polygons represent walls with a specified porosity and height that are used during the 2D simulation process. A porous wall collinear with the boundary of a 2D zone overrides the boundary condition. It is possible to set parameters for the porous wall object that results in the full or partial removal of the wall during a simulation.

This example has a selection of porous walls and porous polygons that have varying properties.

In the GeoPlan, examples of porous walls and porous polygons, with the first porous polygon selected and highlighted in red.

These properties can be viewed or changed in the Properties window.

  1. Open the Properties window of the first porous polygon.

The Properties window for the selected porous polygon.

  1. Note the Porosity value.

This must be a value between 0 and 1, where 0 is impermeable and 1 is fully porous, meaning it has no impact on the flow. As an example, a low porosity in the range of 0.05 - 0.2 may be used to represent a building.

  1. Expand the Crest level drop-down to choose from 3 options: Infinite, Height, and Level.

This is the point up to which the porosity applies—above this, there will be no effect.

  1. Expand the Remove wall during simulation drop-down, which also has 3 options: Never, Fully, or Partially.

For the Partially option, only faces of the wall meeting the criteria are removed. This option can be used to simulate wall collapse.

  1. Select No rainfall to apply no rainfall within the polygon—an option only available for porous polygons.

To best demonstrate the effect of these objects, in this example, a simulation is run with the porous walls and polygons included.

In a running rainfall simulation, with water represented in blue with red flow arrows, more water flows through the polygons with greater porosity values, and builds up to a higher depth behind the polygon with lower porosity.

As the water passes through the objects, the porosity takes effect. Those with lower porosity have a higher depth building up behind them and are the first to be removed when the height threshold is reached.

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