Mooring

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Description MOORING section of input file

The reference manual in pdf can be found here.

A mooring system consists of a collection of lines which hang down from a body. Only one mooring system can be defined per body. The shape of a mooring line is given by the position of its anchor (first element) and the position of the fairlead which connects the line to the vessel. A line is made of segments which have different mechanical characteristics. A segment is divided in element of size length in the dynamic model. The indexation of the line’s segments or elements starts from the anchor and goes up to the fairlead.

As from release v10.3 extra functionalities are added to aNySim for the design of mooring systems. The input for these funtionalities can be given in the [MooringPrepar]-section. A description of the functionalities can be found in that section.

As from release v10.4.0 seabed slopes are implemented in aNySim. A description of global and local seabed slopes can be found here.


[GENERAL]

Keyword Unit Description Options Version
Application [-] Selection of analysis type, can be one of the following:
- Simulation
- MooringPrepar
Optional, default = Simulation aNySim_v10.3


[ENVIRONMENT]

Keyword Unit Description Options Version
SeabedSlope [deg] Global seabed slope: vertical angle between seabed plane and horizontal plane. Applies to all mooring systems. See documentation reference above for definition. Optional aNySIM_v10.4
SeabedAzimuth [deg] Horizontal orientation of the seabed slope relative to the global X-axis. See documentation reference above for definition. Compulsory if SeabedSlope is given aNySIM_v10.4
WaterDepth [m] Water depth at the origin of the global coordinate system. Compulsory if SeabedSlope is given aNySIM_v10.4
WaterDensity [kg/m3] Water density Optional,
default = 1025 kg/m3
aNySIM_v8.0
Gravity [m/s2] Gravity acceleration Optional,
default = 9.81 m/s2
aNySIM_v8.0
GroundAbs [m] Ground absorption: the static impression of the seabed due to the weight of an anchor line element. Only applied with a dynamic model of a mooring system (mooring line divided into elements connected by nodes). The actual (dynamic) impression may be larger due to the vertical velocity of the node. Optional,
default = 0.25 m
aNySIM_v8.0


[BODY#]

Keyword Unit Description Options Version
MooringSystemIndex [-] Index of the mooring system which is connected to this body Optional, refers to the MooringSystem section (if not present then this body has no mooring system) aNySIM_V8.0
MooringSystemOrigin [m,m,m] Position of the mooring system origin in the local coordinate system of the body {X, Y, Z } aNySIM_V8.0

* Add keyword Draft if load is combined with mooring!
The number of mooring systems is given by the number of bodies that are moored.

[MOORINGSYSTEM#]

This section is to be repeated for every type of mooring system. If several mooring systems are identical then they will share the same section: [MooringSystem1].

Keyword Unit Description Options, or comments Version
MooringSystemType [-] 1 = spread mooring (or fixed turret mooring)
2 = free rotating turret
aNySIM_V8.0
IsDynamic [-] True = dynamic model
False = static model
Optional (False by default) aNySIM_V8.0
Nline [-] Number of mooring lines aNySIM_V8.0
NstepDynamic [-] Array of size Nline, containing the nr of extra calls per line to LineDynamic within a communication interval. Values must be > 0. Optional, if not present no extra calls. aNySim_v9.0
LineDef [-] Array of indices which refer to the section where the line is defined. The array is made of Nline values, the first value corresponds to the first line and so on. aNySIM_V8.0
FairleadX [m] Array with fairlead X coordinates relative to MooringSystemOrigin idem aNySIM_V8.0
FairleadY [m] Array with fairlead Y coordinates relative to MooringSystemOrigin idem aNySIM_V8.0
FairleadZ [m] Array with fairlead Z coordinates relative to MooringSystemOrigin idem aNySIM_V8.0
SeabedSlope [deg] Array with local seabed slopes at anchors. See documentation reference above for definition. This key may not be present if a global seabed slope is given in the [Environment] section Optional. Size of array is Nline. aNySIM_v10.4
SeabedAzimuth [deg] Array with local seabed azimuths at anchors. See documentation reference above for definition. Compulsory if the local seabed slopes are given. Size of array is Nline. aNySIM_v10.4
AnchorDepth [m] Array with water depths at anchors. Compulsory in case if local seabed slopes is not used. Size of array is Nline. aNySIM_V8.0
AnchorAlloc [-] 1 = pretension
2 = pretension angle
3 = anchor position: X & Y (note: Z = AnchorDepth or dependent on slope)
4 = azim + radius
Compulsory, the allocation method is the same for all lines. aNySIM_V8.0
IsBreakable [-] Array of booleans. If a switch is true then the tension is set to null as soon as a the line breaks. A line breaks if:
1) the tension exceeds a break load of one of its segments;
2) the tension exceeds a user defined break load, if given;
3) the simulation time exceeds a user defined break time, if given.
Optional, default = false aNySIM_V8.0
UserDefBreakLoad [kN] Array with user defined break load per line. Optional, default = 1010 kN aNySIM_V8.0
UserDefBreakTime [s] Array with user defined break time per line. Optional, default = 1010 s aNySIM_V8.0



The 4 possible ways of defining the anchor position are handled separately.

Allocation by pretension:

Keyword Unit Description Options, or comments Version
AnchorAlloc [-] 1 = pretension aNySIM_V8.0
Pretension [kN] Array containing the pretension value (at fairlead) for every line. The array is made of Nline values, the first value corresponds to the first line and so on. aNySIM_V8.0
AnchorAzim [deg] Array containing the azimuth angle for every line. This is the horizontal angle made by the vector fairlead to anchor with the x-axis of the earth fixed referential. For aNySIM-versions below 12, this is the x-axis of the local ship referential. aNySIM_V8.0


Allocation by pretension angle:

Keyword Unit description Options, or comments Version
AnchorAlloc [-] 2 = pretension angle aNySIM_V8.0
PretensionAngle [deg] Array containing the pretension angle (at fairlead) for every line. This is the angle of the line with the water plan The array is made of Nline values, the first value corresponds to the first line and so on. aNySIM_V8.0
AnchorAzim [deg] Array containing the azimuth angle for every line. This is the horizontal angle made by the vector fairlead to anchor with the x-axis of the earth fixed referential. For aNySIM-versions below 12, this is the x-axis of the local ship referential. aNySIM_V8.0


Allocation by anchor position:

Keyword Unit Description Options, or comments Version
AnchorAlloc [-] 3 = anchor position aNySIM_V8.0
AnchorX [m] Array containing the x-coordinate w.r.t. the mooring system origin for every line. The array is made of Nline values, the first value corresponds to the first line and so on. aNySIM_V8.0
AnchorY [m] Array containing the y-coordinate w.r.t. the mooring system origin for every line. idem aNySIM_V8.0


Allocation by radius and azimuth:

Keyword Unit Description Options, or comments Version
AnchorAlloc [-] 4 = anchor position by radius and azimuth angle aNySIM_V8.0
AnchorRadius [m] Array containing the distance between fairlead and anchor for every line. The array is made of Nline values, the first value corresponds to the first line and so on. aNySIM_V8.0
AnchorAzim [deg] Array containing the azimuth angle for every line. This is the horizontal angle made by the vector fairlead to anchor with the x-axis of the earth fixed referential. For aNySIM-versions below 12, this is the x-axis of the local ship referential. aNySIM_V8.0


[LINEDEF#]

This section gives the description of a line type. A line type can be modelled either with one or more segments or with a Load-Elongation Curve (LEC).In case segments are used the catenary formulation (static run) or the lumped-mass method (dynamic run) is applied. In case of a LEC the tensions are found by linear interpolation.

When segments are used the key "Nsegment" must be given, when a LEC is used the key "Npoint" must be given, they may not be both present.

Keyword Unit Description Options, or comments Version
Nsegment [-] Number of segments Compulsory if Npoint is not given aNySIM_V8.0
Npoint [-] Number of points describing the LEC. Compulsory if Nsegment is not given aNySIM_V10.4
LineSegmentType [-] Array containing the different types of segments that makes the line. This index is used in the section [LineSegmentType#] Compulsory if Nsegment > 0.
The array is made of Nsegment values, the first value corresponds to the first segment and so on (starting at the anchor).
aNySIM_V8.0
Length [m] Array containing the length of every segment Compulsory if Nsegment > 0 aNySIM_V8.0
NrElement [-] For a dynamic run: every segment is divided in elements. This array gives how many elements must be used per segment. Compulsory if Nsegment > 0 and line dynamics are to be applied (IsDynamic = true in MooringSystem section). aNySIM_V8.0
Nbuoy [-] Number of buoys on this line Optional if Nsegment > 0
Default is 0 (no buoy)
aNySIM_V8.0
BuoyType [-] Array containing the different types of buoys. Any of those indexes refers to the section [buoy#] where the buoy is defined Compulsory if Nbuoy > 0
The array is made of Nbuoy values, the first value corresponds to the first buoy and so on
aNySIM_V8.0
SegmentBuoy [-] Array containing every index of a segment where a buoy is attached to. The buoy is added at the end of the segment (oposite of the anchor side) Idem aNySIM_V8.0
Nclump [-] Number of clumps on this line Optional if Nsegment > 0
Default is 0 (no clump)
aNySIM_V8.0
ClumpType [-] Array containing the different types of clumps. Any of those indexes refers to the section [clump#] where the clump is defined Compulsory if Nclump > 0
The array is made of Nclump values, the first value corresponds to the first clump and so on
aNySIM_V8.0
SegmentClump [-] Array containing every index of a segment where a clump is attached to. The clump is added at the end of the segment (oposite of the anchor side) idem aNySIM_V8.0
HorDist [m] Array of size Npoint with horizontal distances between anchor and fairlead. Values must be in increasing order. Compulsory if Npoint > 0 aNySIM_V10.4
TopTension [kN] Array of size Npoint with line tensions at the fairlead. Compulsory if Npoint > 0 aNySIM_V10.4
TopAngle [deg] Array of size Npoint with line angles at the fairlead, 00 indicates a horizontal line at the fairlead, 900 a vertical line. The horizontal and vertical components of the line tensions are derived from these angles. Compulsory if Npoint > 0 aNySIM_V10.4


[LINESEGMENTTYPE#]

This section gives the description of a segment. These data can be given in a separate file (MooringTypeDatabase).


Keyword Unit Description Options, or comments Version
Wsub [N/m] Submerged weight per meter Compulsory aNySIM_V8.0
Mass [kg/m] Mass per meter Complsory aNySIM_V8.0
Breakload [kN] Breaking load Compulsory aNySIM_V8.0
EAType [-] 1 = linear EA
2 = LEC
3 = polyprop / polyester
4 = nylon double braided
5 = nylon 3-strand
6 = nylon 8-strand
7 = Dyneema
Compulsory aNySIM_V8.0
EA [kN] Linear elasticity coefficient Compulsory if EAType = 1 aNySIM_V8.0
LoadRatio [-] Array with fractions of break load. Values must be in increasing order. Compulsory if EAType = 2 aNySIM_V10.4
ElongRatio [-] Array with fractions of length. Values must be in increasing order. Compulsory if EAType = 2 aNySIM_V10.4


The following items are used for a dynamic run, not for a static run.


Keyword Unit Description Options, or comments Version
Diameter [m] Diameter Optional, default = 0 aNySIM_V8.0
Cin [-] Inertia coefficient in normal direction Optional, default = 0 aNySIM_V8.0
Cit [-] Inertia coefficient in tangential direction Optional, default = 0 aNySIM_V8.0
Cdn [-] Drag coefficient in normal direction Optional, default = 0 aNySIM_V8.0
Cdt [-] Drag coefficient in tangential direction Optional, default = 0 aNySIM_V8.0
Cfn [-] Bottom friction coefficient in normal direction Optional, default = 0 aNySIM_V8.0
Cft [-] Bottom friction coefficient in tangential direction Optional, default = 0 aNySIM_V8.0


[BUOYTYPE#]

This section gives the description of a type of buoy. This section is compulsory if this type of buoy is refered to in a section [LINEDEF#].


Keyword Unit Description Options, or comments Version
Type [-] 1 = vertical cylinder
2 = perpendicular horizontal cylinder
3 = parallel horizontal cylinder
4 = sphere
Compulsory aNySIM_V8.0
Mass [kg] Mass Compulsory aNySIM_V8.0
Volume [m3] Volume Compulsory aNySIM_V8.0
Diameter [m] Diameter Compulsory aNySIM_V8.0
Cin [-] Inertia coefficient in normal direction Compulsory for dynamic runs aNySIM_V8.0
Cit [-] Inertia coefficient in tangential direction Compulsory for dynamic runs aNySIM_V8.0
Cdn [-] Drag coefficient in normal direction Compulsory for dynamic runs aNySIM_V8.0
Cdt [-] Drag coefficient in tangential direction Compulsory for dynamic runs aNySIM_V8.0


[CLUMPTYPE#]

This section gives the description of a type of clump. This section is compulsory if this type of clump is refered to in a section [LINEDEF#].


keyword unit description Options, or comments Version
Mass [kg] Mass Compulsory aNySIM_V8.0
SubmWeight [N] Submerged weight Compulsory aNySIM_V8.0


[MOORINGSETTINGS]

Some keywords enable to overwrite some of the default parameters which are used by the LineStatic library and the LineDynamic library. These settings are regrouped in this section. This section is fully optional. Every keyword of this section is optional.

Keyword Unit Description Options, or comments Version
IsDyncatIntFile - Boolean switch intended for debug session Provisory, default = false aNySIM_V8.0
StaticForce [kN] EF force vector at fairlead at t= 0 s Provisory, default = 0 aNySIM_V8.0
IsCompensation [-] Array with 3 boolean switches. The compensation force is the force due to the vertical component of the mooring force at t= 0s. This force is applied to the MSO. This force is subtracted from the total resulting EF force at t if the first switch is true. If the second switch is true then the roll moment at CoG caused by the transfer of the compensation force from MSO to CoG is also subtracted from the roll moment. If the third switch is true then the pitch moment caused by the transfer of the compensation force from MSO to CoG is also subtracted from the pitch moment. Static and dynamic. Default = false aNySIM_V8.0
NTMAX - Maximum of number of times that the communication time step can be divided by 2 in case a solution cannot be found for the requested top motion Dynamic, default = 32 aNySIM_V8.0
TMAXIT - Maximum of number of iterations in the Newmark iteration to reach a solution Dynamic, default = 5 aNySIM_V8.0
EATTOL [N] Tolerance applied on the variation of the tension in every element of the line Dynamic, default = 1000 aNySIM_V8.0
IPORT - Parameter used in the convergence criteria Dynamic, default = 0 aNySIM_V8.0
TCRIT - Parameter used inthe convergence criteria Dynamic, default = 105 aNySIM_V8.0
TPORT - Parameter used in the convergence criteria Dynamic, default = 0.05 aNySIM_V8.0
IsShapeOutput - Boolean switch. If true then the initial shape of all line of a mooring system is reported a distinct file per mooring system. The x-coordinate in StaticShape#.txt is given along the line i.e. in the XY-plane. Dynamic, default = false aNySIM_V8.0
ICOMPR - Tension/compression switch:
-2: in case of compression: lengths of all elements are shortened
-1: in case of compression: lengths of elements at seafloor are shortened
0: compression not allowed, tension is set at small positive value
1: compression allowed, element lengths follow from compression force
Dynamic, default = 0 aNySIM_v10.4
CFMAX - Contraction factor, used with options ICOMPR = -2 and ICOMPR = -1 Dynamic, default = 0.5 aNySIM_v10.4



[Output]

The following signals can be written in the output files.

Alias Index 1 Index 2 Description Unit Version
‘Fmoor’ iBody iMode
= 1..6
Total mooring forces acting on the body with index iBody [kN, kNm] aNySIM_V8.0
‘TAnch’ iMooring iLine Tension at anchor in line with index iLine of mooring system with index iMooring [kN] aNySIM_V8.0
‘TFair’ iMooring iLine Tension at fairlead in line with index iLine of mooring system with index iMooring [kN] aNySIM_V8.0
‘DxFair’ iMooring iLine x-EF motion at fairlead of line with index iLine of mooring system with index iMooring [m] aNySIM_V8.0
‘DyFair’ iMooring iLine y-EF motion at fairlead of line with index iLine of mooring system with index iMooring [m] aNySIM_V8.0
‘DzFair’ iMooring iLine z-EF motion at fairlead of line with index iLine of mooring system with index iMooring [m] aNySIM_V8.0
‘MsoPos’ iMooring iMode
= 1..6
EF position of mooring system origin of mooring system with index iMooring [m, deg] aNySIM_V8.0
‘TnMS#’ iLine iNode Tension at node with index iNode of line with index iLine of mooring system # [kN] aNySIM_V8.0
‘XnMS#’ iLine iNode x-EF position of node with index iNode of line with index iLine of mooring system # [m] aNySIM_V8.0
‘YnMS#’ iLine iNode y-EF position of node with index iNode of line with index iLine of mooring system # [m] aNySIM_V8.0
‘ZnMS#’ iLine iNode z-EF position of node with index iNode of line with index iLine of mooring system # [m] aNySIM_V8.0


In case of the following situation the following node numbering is found:

Mooringlinenumbering.jpg

Using TnMS#,#,3 the tension found at node 3 is given above the buoy i.e. node 5 in the numbering in blue.