*Calm Model

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*Calm Model

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Purpose

To specify the properties of calm buoys.

Theory

Refer to CALM Buoy for further information on this feature.

Keyword Format

A block of five lines defining the calm buoy properties.

Node (Number or Label)

M11, I11, I22, I33

A11, A33, A55, A15

K33, K44

D11, D33, D55, D15

 

where:

 Node        =        the node of the finite element mesh located at the buoy Centre of Gravity. If you specify a node label rather than a node number, it must be enclosed in {} brackets.

 M11        =        M22        =        M33        =        mass of buoy

 I11        =        roll inertia of the buoy

 I22        =        pitch inertia of the buoy

 I33        =        yaw inertia of the buoy

 A11        =        surge added mass

 A33        =        heave added mass

 A55        =        pitch added mass

 A15        =        coupled surge pitch added mass

 K33        =        heave stiffness

 K44        =        K55        =        roll and pitch stiffness terms

 D11        =        surge damping

 D33        =        heave damping

 D55        =        pitch damping

 D15        =        coupled surge pitch damping

 

Table Input

Input:

Description

Node:

The node (number or label) of the finite element mesh located at the buoy Centre of Gravity. If you specify a node label rather than a node number, it must be enclosed in {} brackets.

Mass:

The mass of the buoy.

Roll Inertia:

The roll inertia of the buoy.

Pitch Inertia:

The pitch inertia of the buoy.

Yaw Inertia:

The yaw inertia of the buoy.

Surge Added Mass:

The added mass in surge.

Heave Added Mass:

The added mass in heave.

Pitch Added Mass:

The added mass in pitch.

Coupled Surge-Pitch Added Mass

The coupled surge-pitch added mass.

Heave Stiffness:

The stiffness (due to buoyancy) in heave.

Roll and Pitch Stiffness:

The stiffness (due to buoyancy) in roll and pitch.

Surge Added Damping:

The added damping in surge.

Heave Added Damping:

The added damping in heave.

Pitch Added Damping:

The added damping in pitch.

Coupled Surge-Pitch Added Damping

The coupled surge-pitch added damping.

Notes

(a)Refer to Model Set-up for further information on how to incorporate a CALM buoy into the finite element model using an assemblage of standard beam-column elements.

(b)Refer to Buoy Properties for further information on the specification of the mass, buoyancy stiffness, added mass and radiation damping matrices.