These characteristic scales directly affect the convergence criteria of the iterative solvers employed in the analysis. Characteristic scalesįor some models it may be desirable to explicitly set a characteristic length and characteristic force for the 6D buoy. If the buoy is not significantly compressible, use the value infinity to mean 'incompressible'. Specifies the compressibility of the buoy. The weight force and moments of inertia are applied at this point. The centre of mass of the buoy, relative to the buoy origin.
How does orcaflex calculate static skin#
To model wave radiation damping the velocity relative to earth should be used, whereas to model skin friction damping the velocity relative to the fluid is appropriate. You can choose whether the buoy velocity to which the damping data apply (see lumped buoy data or spar buoy or towed fish data) is relative to earth or relative to the fluid. The off-diagonal terms are taken to be zero, so the buoy axes should be chosen to be in the principal directions of inertia about the centre of mass. These moments of inertia are the diagonal terms in the structural inertia matrix about the specified centre of mass. The initial attitude is given by the three angles rotation 1, rotation 2, rotation 3, which are successive rotations that define the orientation of the buoy axes, $(B\urm$ axes through the buoy centre of mass. $x$, $y$ and $z$ connection coordinates that determine the initial position of the buoy origin. ConnectionĪ 6D buoy can be free, fixed, anchored or connected to another object. Disturbance vesselĭetermines whether the 6D buoy will experience sea state disturbance generated by a particular vessel. The default value is specified by environment, meaning that the method specified on the environment form will be used you can override that (for this buoy) by selecting a different method here if you wish. The wave calculation method to be used when computing the buoy's wave kinematics. The following data items are common to all types. Three types of buoy are available: lumped buoys, spar buoys and towed fish.
The origin of the buoy axes $\Bxyz$ can be anywhere, but the axes directions should be coincident with the principal axes of structural inertia of the buoy.
All types of 6D buoy use a local buoy axes coordinate system.
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