Current Data Inputs

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Current Data Inputs

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current

Input

Description

Type:

A drop-down list that allows you to specify the type of current being specified, which may be Uniform, Piecewise Linear or Power Law.

Water Surface:

A drop-down list that allows you to specify how PipeLay handles variations in current with variations in water level due to waves. The options available are Ambient or MWL (Mean Water Level).  The default is Ambient.

If you select Ambient, the current velocity distribution is stretched so that the velocity at the ambient water surface is constant throughout the analysis.

If you select MWL, the current velocity distribution remains unaltered throughout the analysis, regardless of the ambient water surface elevation.

This drop-down list is only available when you select Piecewise Linear or Power Law from the Type drop-down list.

Current Data

Click on this button to display a dialog where you specify more detailed current information. The dialog that is displayed varies depending on the option that you select from the Type drop-down list. The following sections describe the dialogs that are displayed.

 

 

Current – Uniform Dialog

current_uniform

Input

Description

Velocity:

The horizontal current velocity.

Units: [m/s] or [ft/s]

Direction:

The current direction, measured anti-clockwise from the global Y direction. Defaults to 0°.

Units: [deg]

 

 

Current – Piecewise Linear Dialog

current_piecewise_linear

Input

Description

Distance Below Mean Waterline:

The depth below the Mean Water Line at which the current velocity and direction are being specified.

A minimum of two points is required to define a piecewise linear current distribution. At depths intermediate to those specified, the current velocity and direction are found by linear interpolation. Below the greatest specified depth, the current velocity and direction are assumed to be constant with values equal to those at the greatest specified depth. Likewise, at depths above the smallest specified depth, the current velocity and direction are assumed to be constant with values equal to those at the smallest specified depth.

Units: [m] or [ft]

Velocity:

The horizontal current velocity at the specified depth.

Units: [m/s] or [ft/s]

Direction:

The current direction at the specified depth, measured anti-clockwise from the global Y direction. The default is 0°.

Units: [deg]

 

 

Current – Power Law Dialog

current_power_law

Input

Description

Reference Elevation:

The reference elevation at which the current velocity is being specified.

The power law profile is governed by the following relationship:

       

where UC is the current velocity at elevation H, HR is the reference elevation and UR is the current velocity at the reference elevation. The current direction is constant throughout the water depth.

Units: [m] or [ft]

Velocity:

The horizontal current velocity at the reference elevation.

Units: [m/s] or [ft/s]

Direction:

The current direction, measured anti-clockwise from the global Y direction. The default is 0°.

Units: [deg]