SMS:BOUSS-2D Using the Model

BOUSS-2D Grid

When using the model, the project will need a BOUSS-2D Cartesian grid. If a grid has already been created or an existing simulation read, the grid object will exist in the Project Explorer and selecting that object will make the Cartesian grid module active.

To create a bouss-2d grid:

1. Right-click on the map data tree item and select new coverage.
2. Select BOUSS-2D.
3. Give the coverage a name then click Ok.
4. Click out a grid frame using the Grid Frame tool.
5. Follow the instructions found at Creating 2D Cartesian Grids.

Boundary Condition data

All numeric models require boundary condition data. In BOUSS-2D, boundary conditions are defined along arcs for porosity/damping, and on nodes for wave-makers.

Damping / Porosity coverage

Damping and porosity coverages contain arcs that represent damping/porosity. The location of the arcs will be the location of the damping/porosity when running a simulation. Assigned to the arcs is the attributes of width and value. Multiple arcs can be created in a single coverage.

To create a damping/ porosity coverage:

1. Right-click on the map data tree item and select new coverage
2. Select BOUSS-2D Damping or Porosity
3. Give the coverage a name then click Ok
4. Select the newly created coverage
5. Click on the Create Feature Arc tool
6. Click out an arc over the grid where the user wants the damping/porosity
7. Click on the Select Feature Arc tool
8. Click on an arc, then right-click and select Attributes

Wave Maker coverage

Wave maker coverages contain points that represent a wave maker. The location of the point will be the location of the wave maker when running a simulation. Assigned to the points are the wave maker settings including type and direction.

To create a wave maker coverage:

1. Right-click on the map data tree item and select new coverage
2. Select BOUSS-2D wave maker
3. Give the coverage a name then click Ok
4. Select the newly created coverage
5. Click on the Create Feature Point tool
6. Click out a point over the grid where the user wants the wave maker
7. Click on the Select Feature Point tool
8. Click on an arc, then right-click and select Attributes

Creating a Constant Depth Wave Maker Platform

The BOUSS-2D model generates waves along the specified wave makers (as described above). In order to increase model stability and allow users to use an internal wave maker, it is necessary that the depths in the grid under a wave maker be relatively constant. For this reason, wave makers should be positioned far enough off shore that an entire row/column of the grid is at a relatively constant water depth. If the depth varies more than 10%, SMS will issue a warning when outputting the model.

To correct this situation, the depth under the wave maker can be adjusted to a constant value, creating a flat area. (This meets the requirements for stability for the BOUSS-2D model. We refer to this flat area as the wave platform.) The steps to create a flat area include:

1. select the cells of the area to be made flat (directly under and adjacent to the wave maker). Use the select cell, select row or select column tools to do this.
2. specify the elevation (remember that BOUSS-2D uses elevations, so depths are negative numbers) in the Z edit field to change the elevation of the selected area.

Example

• Assume the grid origin (I=1, J=1)is offshore, and user wants to place the wavemaker at the I=50 column.
• Assume the average elevation of all cells between I=1 and I=50 is -30 m.

Steps

1. Select all the cells in columns 1 through 50
2. Specify an elevation of -30 m in the Z edit field

Notes

• SMS computes the average depth of all selected cells. This is displayed in the Z edit field when multiple cells are selected.
• The average depth could be chosen by selecting the row or column where the wave maker will be placed. However,
• Selecting a few rows/columns using the shift key to add to the selection in the region of the wave maker displays the average elevation for a larger region. This average may blend into the natural bathymetry with less the irregularity.
• Individual rows/columns can be selected with the SMS grid tools. Larger regions can be selected using the select cell tool and holding down the control key and dragging a box. The alt key can be used to just add new cells to the selection list.
• The constant elevation area should extend for several columns/rows behind and in front of the wavemaker. The rule of thumb is to select all the rows/columns within half-wavelength from the wavemaker.

Related Topics

• BOUSS-2D