Regular Analysis

1. Analysis Parameters

  • Periods : Number of periods for regular wave analysis

  • Time steps : Number of integration time steps per period

  • Wave acting : Wave acting or not.

  • Support vessel motion: Options are

    • Generated motions: Support vessel motions calculated from wave period, wave amplitude and motion transfer function

    • No motions : Switch off vessel motion. Body motions will be included if the model contains bodies.

    • Specified motions : Support vessel motions specified directly using motion amplitude and phase angles, see Regular Vessel motion.

No motions must be specified if the model does not contain a support vessel.

2. Wave calculation method

2.1. Wave theory and kinematics

Wave theory :

  • Airy linear : Airy linear wave theory

  • Stoke 5th order: Stoke 5th order wave theory

Kinematics in the wave zone:

  • Mean water level: Wave kinematics and wave loads calculated to the mean water level

  • Stretching and compression of wave potential

  • Moving the potential to actual surface

  • Keeping the potential constant from mean water level to wave surface when the surface is above the mean water level

  • Second order wave with integration of wave forces to wave surface

See illustration of wave kinematics in in Wave kinematics and the wave surface- 1: to mean water level, 2: profile stretched / compressed, 3: profile moved .

The options for kinematics in the wave zone are only relevant for Airy linear wave theory.
The combination of integration of wave forces to the wave surface and MacCamy-Fuchs or Potential hydrodynamic loads is not consistent. MacCamy-Fuchs / Potential loads are calculated to the mean water level at the static position. Additional loads (e.g. drag) will be applied up to the wave surface.

Kinematics position: Choice of position and method for calculation of wave kinematics. Options are

  • Dynamic position: Kinematics are calculated at the dynamic position during the simulation.

  • Static position: Kinematics are calculated at the static position during the simulation.

2.2. Regular Vessel motion

Regular vessel motion is specified of the option Specified motion is chosen.

  • Support vessel :

  • Xamp : Motion amplitude, global x-direction

  • Yamp : Motion amplitude, global ydirection

  • Zamp : Motion amplitude, global zdirection

  • Zramp : Motion amplitude, global x-rotation

  • YRamp : Motion amplitude, global y-rotation

  • ZRamp: Motion amplitude, global z-rotation

  • Xpha : Phase angle, x-motion

  • YPha : Phase angle, y-motion

  • Zpha : Phase angle, z-motion

  • ZRpha: Phase angle, x-rotation

  • TRpha : Phase angle, y-rotation

  • ZRpha : Phase angle, z-rotation