Quadratic Current Coefficients

The Quadratic current Coefficient editor allows you to define current force coefficients for a body. Current forces are calculated based on the current velocity and the specified coefficients.

1. Type

Two types of current coefficients are available:

1.1. Classic

Classic current coefficients are given as a function of the relative current direction only.

1.1.1. Symmetry

The symmetry option determines how current coefficients are specified across different directions:

  • No symmetry: Coefficients must be specified for the full range [0, 360] degrees. Coefficients at 0 and 360 degrees must be equal.

  • Symmetry about Y=0: Coefficients are specified for [0, 180] degrees. Both 0 and 180 degrees must be included. This represents single symmetry about the x-z plane.

  • Double symmetry: Coefficients are specified for [0, 90] degrees. Both 0 and 90 degrees must be included. This represents double symmetry about both x-z and y-z planes.

1.1.2. Current coefficients

The coefficient table displays the current force coefficients for each direction. Each row contains:

  • Direction: Current direction, [deg]

  • Current force coefficients for degrees of freedom 1-3 \(N \cdot s^2/m^2\), and 4-6 \(N \cdot s^2/m\)

    • C21: Quadratic current force coefficient in surge

    • C22: Quadratic current force coefficient in sway

    • C23: Quadratic current force coefficient in heave

    • C24: Quadratic current force coefficient in roll

    • C25: Quadratic current force coefficient in pitch

    • C26: Quadratic current force coefficient in yaw

1.2. Position dependent

Position dependent current coefficients are given as a function of:

  • Relative current direction

  • Body vertical position

  • Body roll angle

  • Body pitch angle

1.2.1. File Name

  • File Name: Path to the external file containing the position dependent current coefficients

The force coefficients in the file must be specified in \(\frac{kN}{\frac{m}{s}}\) for translational degrees of freedom and \(\frac{kN}{s}\) for rotational degrees of freedom.

See description of the external file format here.