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*Seabed Profile |
 
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*Seabed Profile
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*Seabed Profile |
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To specify the seabed profile/bathymetry.
Refer to Seabed Interaction for further information on this feature.
A block of two lines which defines the seabed profile. The first line defines the type of specification, Sloping, 2D or 3D, and the format of the second line depends on the specification type.
For a uniformly sloping seabed, the keyword format is as follows:
TYPE=SLOPING
[DIRECTION=Seabed Direction]
SLOPE=Seabed Slope
For 2D seabed profiles the keyword format is as follows:
TYPE=2D
[INTERPOLATION=Interpolation Method][, DIRECTION=Seabed Direction]
FILE=File Name
For 3D seabeds the keyword format is as follows:
TYPE=3D
[INTERPOLATION=Interpolation Method]
FILE=File Name
The Seabed Slope is measured in degrees. A sloping seabed is assumed to pass through the global origin. See Note (b).
The Seabed Direction is optional. It is measured in degrees and rotates the seabed profile counter-clockwise about the global X axis.
The Interpolation Method is optional. For a 2D seabed it may be LINEAR (the default), CUBIC SPLINE or CUBIC BESSEL. For a 3D seabed it may be LINEAR (the default) or CUBIC.
For 2D or 3D seabed profiles the file File Name is a binary file generated by the Seabed Utility application and has the extension .FCSBD. See Notes (c) and (d).
Additionally, for backward compatibility, the file File Name for linear 2D seabed profiles may be specified as a text file. See Note (e). In this case, the format of the external ASCII data file is as follows:
A block of lines defining various points on the arbitrary seabed. The line may be repeated as often as necessary to completely define the seabed profile.
Y Co-ordinate, Seabed Elevation
Input: |
Description |
Seabed Direction: |
The orientation of the seabed measured in degrees counter-clockwise about the global X axis. This value defaults to zero if omitted. |
Seabed Slope: |
The slope of a uniformly sloping seabed, in degrees. This defaults to a value of 0.0 degrees, which gives a horizontal seabed. See Note (b). |
Input: |
Description |
Interpolation Method: |
This option allows you to specify how the seabed is interpolated between the seabed data points. The options are LINEAR (the default), CUBIC SPLINE or CUBIC BESSEL. |
Seabed Direction: |
The orientation of the seabed measured in degrees counter-clockwise about the global X axis. This value defaults to zero if omitted. |
Seabed File Name: |
The name of the seabed file containing the 2D seabed profile data. See Note (c). |
Input: |
Description |
Interpolation Method: |
This option allows you to specify how the seabed is interpolated between the seabed data points. The options are LINEAR (the default) or CUBIC. |
Seabed File Name: |
The name of the seabed file containing the 3D seabed profile data. See Note (d). |
(a) If *SEABED PROPERTIES is specified but this keyword is omitted, then a default horizontal seabed is assumed. In this case the seabed is coincident with a plane at zero global X elevation (the global YZ plane).
(b) If the sloping seabed option is invoked, a uniformly sloping seabed is modelled which passes through the global origin of co-ordinates. The seabed slope is specified in degrees, and a positive slope defines a seabed sloping upwards in the positive global Y direction, while a negative slope gives a seabed sloping in the opposite direction. Optionally, the sloping seabed can be rotated about the global X axis by specifying a Seabed Direction.
(c) The profile of the 2D seabed varies in the global XY plane and is then extruded horizontally along the global Z direction. The profile is defined in the seabed file (.FCSBD) by a series of pairs of values. The file is created using the Seabed Utility standalone application. LINEAR, CUBIC SPLINE or CUBIC BESSEL interpolation is used to determine the surface profile between user specified points, while outside the range of points the surface is assumed to be flat and horizontal. Optionally, the 2D seabed can be rotated about the global X axis by specifying a Seabed Direction.
(d) The profile of the 3D seabed is defined in a binary seabed file (.FCSBD) by a series of global XYZ coordinate values lying on the seabed surface. The seabed file is created using the Seabed Utility standalone application and has the .FCSBD extesion. LINEAR or CUBIC interpolation may be used to determine the surface elevation between user specified points, while outside the boundary of the point set the surface elevation is assumed to be infinitely deep.
(e) For text based 2D seabed files, the profile is defined by a series of pairs of values. This is the data that is contained in the ASCII data file. Each line in the file defines a point on the profile and contains data in the format Y-coordinate, Seabed Elevation. Here Y-coordinate is self-explanatory, and Seabed Elevation is the height of the seabed at this point above the datum X=0.
(e) In the default case of a flat seabed, the seabed is coincident with a plane at zero datum (the global YZ plane).
(e) If the sloping seabed option is invoked, a uniformly sloping seabed is modelled which passes through the global origin of co-ordinates. The seabed slope is specified in degrees, and a positive slope defines a seabed sloping upwards in the positive global Y direction, while a negative slope gives a seabed sloping in the opposite direction.
(e) The profile of the arbitrary 2D seabed varies in the global XY plane and is constant in the global Z direction. The profile is defined by a series of pairs of values, and this is the data that is contained in the ASCII data file. Each line in the file defines a point on the profile and contains data in the format Y-coordinate, Seabed Elevation. Here Y-coordinate is self-explanatory, and Seabed Elevation is the height of the seabed at this point above the datum X=0. Linear interpolation is used to determine the surface profile between user-specified points, while outside the range of points the surface is assumed to be flat and horizontal.