AQWA Training Course
Dr Shuangxing Shuangxi ng Du ANSYS A NSYS Inc. Inc .
The topics covered in the training course are as follows: • description of program capabilities • theoretical background • modelling techniques • analysis procedure • data requirements and preparation • description of output and interpretation of results • worked examples
The topics covered in the training course are as follows: • description of program capabilities • theoretical background • modelling techniques • analysis procedure • data requirements and preparation • description of output and interpretation of results • worked examples
AQWA Programs
• Structure and Capabilities of AQWA Programs – AQWA LINE
• 3-D diffraction & radiation analysis program for wave force and hydrodynamic property calculations; hydrostatic analysis LIBRIUM – AQWA LIBRIUM • Structure equilibrium position and force balance calculations; eigen mode and dynamic stability analysis – AQWA FER
• Spectral analysis of structure motion (wave frequency or/and drift frequency) and mooring tension in irregular waves
AQWA Programs – AQWA NAUT • Time domain program for wave frequency structure motion and mooring tension analyses in large waves
– AQWA DRIFT • Time domain program for drift frequency and wave frequency structure motion and mooring tension analysis in irregular waves
– AQWA Graphical Supervisor (AGS) • AQWA pre and post processor; on-line analysis
– AQWA WAVE • Interface program to transfer wave loads from AQWA LINE to a FE model for structural analysis
General Relations between Programs
AGS
ANSYS
LINE
LIBRIUM
FER
WAVE
NAUT
DRIFT
ASAS (FE mo del)
EXCEL
Typical AQWA Models
Moored Tanker
Semi Sub
Typical AQWA Models Spar Transportation
FPSO
Ship in channel
JACK-UP
FPSO+TLP CONCEPT
MANY SHIPS
SEMI-SUB
LIFTING
GREEN OCEAN ENERGY
ANSYS-t A NSYS-to o -A -AQW QWA A Int In t er erff ac ace e
AGS A GS mes m esh h g en ener erat atii o n
AGS A GS Pos Po s t -p -prr o c es ess sing
Force & Response Curves
Shear Force & Bending Moment
AGS Post-processing
Wave surface contour
Pressure contour
Diffracted wave surface
●
Installation AQWA, AGS and AQWA-WAVE AQWA Manuals and examples
AGS demonstration
●
Open - Open/close, and save AQWA models Edit - Create and edit AQWA models Run - Perform an AQWA analysis on the presently loaded model Graphs - Display and manipulate AQWA results graphically Plots - Display and edit AQWA models visually Cable Dynamics - Define and analyze problems involving cable dynamics Help - Access to the online help system
AQWA Global Coordinate System
AQWA Global Coordinate System is referred to as z the Fixed Reference Axes (FRA):
y • • • •
the origin lies in the still water W.L. 0 plane the positive z axis is vertically upwards a right handed system it is not related to the directions North, South, East and West
x
p = ρ Z 0
Hydrostatic z
Rigid body motions: Surge, Sway, Heave - translational Roll, Pitch, Yaw - rotational
y Port side
Stern
Bow
Starboard side
Archimedes’s principle Buoyancy of an immersed body = weight of the fluid displaced G
Hydrostatic pressure p = ρ Z 0
Z0
B
G: centre of gravity B: centre of buoyancy Buoyancy is the resultant of all hydrostatic force over wetted surface
x
Directions in AQWA –
The wave, wind and current directions are defined in AQWA as the directions which they are travelling towards.
–
The direction is defined as the angle between the wave (or current, wind) and the positive x axis measured anticlockwise.
–
Directions in AQWA are input and output in degrees.
Y
Wave direction (or current, wind)
positive angle X axis
Phase Angle –
In AQWA, the phase angle (Φ in degrees) of a parameter defines the time difference (dt) from the time when the wave crest is at the CoG of the structure to the time when the parameter reaches its peak value. (dt= Φ*T/360, where T is the wave period).
– A positive phase angle indicates that the parameter
lags behind the wave.
Waves in AQWA Wave Types: 1)
Airy Waves (linear wave) a = A cos (-ωt + kx) (ω: frequency in radians/sec; k: wave number) Used in AQWA LINE, LIBRIUM, FER, DRIFT, NAUT (optional)
2)
Stokes 2nd Order Waves a = A cos (-ωt + kx) + 0.5 k A² cos2(-ωt + kx) Used in AQWA NAUT by default
Waves in AQWA
Wave Forms: 1)
Regular Waves Used in AQWA LINE, NAUT (by default)
2)
Irregular Waves ● Defined by a wave spectrum and used in AQWA LIBRIUM, FER, DRIFT, NAUT ● Imported time history of wave elevation used in AQWA DRIFT
Waves in AQWA Wave spectrum types accepted in AQWA are: a. b. c. d.
P-M spectrum JONSWAP spectrum User defined spectrum Gaussian spectrum for Cross Swell
Irregular waves can be in the form of: a. Long crested waves; OR b. Short crested waves, ie a spread sea (only for AQWA LIBRIUM and FER)
Wind and current in AQWA Wind types accepted in AQWA are: a. Uniform wind b. Ochi and Shin wind spectrum c. API wind spectrum d. NPD wind spectrum e. User-defined wind spectrum Current types accepted in AQWA are: a. Uniform current b. Profiled current velocity
Wave Forces on Structures • For Diffracting Structures (modelled with plate elements) -
Incident wave force (Froude-Krylov force): from the pressure in the undisturbed waves.
-
Diffraction force: due to stationary structure disturbing the incident waves.
-
Radiation force: due to structure’s oscillation which generates waves.
-
Drift force (net force due to high order effect)
hydrodynamic forces on structures (1) on Diffraction elements
Fluid force
Hydrodynamic
Wave exciting force
Ambient pressure (incident wave or Froude-Krylov force)
Effect of structure on waves (Diffraction)
F(ω)
Hydrostatic
Radiation force due to structure motion
In-phase (Added Mass)
Out-of-phase (Radiation damping)
Ma(ω).x″
C(ω).x′
K.x
hydrodynamic forces on structures (2) on Morison elements
• For Morison Structures (modelled with Morison elements, eg TUBEs, DISCs) -
Morison force (including drag) calculated using Morison equation.
Morison Force Equation for Morison force calculation For slender cylindrical elements (D/λ<0.2), e.g. tube elements, the hydrodynamic force on unit length of the element can be calculated using Morison equation: 1 F = ρ Ωa w + ρ C a Ωa w − ρ C a Ω X + ρ C d DV V 2
Ca and Cd are the added mass and drag coefficients of the element; Ω is the volume of the element (per unit length) D is the element diameter, V is the relative velocity. Radiation force Froude-Krylov force Wave inertia force
Drag force
AQWA LINE - Introduction – AQWA-LINE is a 3D diffraction and radiation analysis program – Frequency domain – Structures are described by a number of panels – Source distribution approach (boundary integration method)
A source is place at the centre of each panel and then the program solves for the source strengths, subject to the boundary conditions: no flow through the hull no flow through the sea-bed a free surface condition
Surface mesh
AQWA LINE - Features – Removal of irregular frequencies by auto-generated lid – Multi-body hydrodynamic interactions (lid to suppress standing waves) – Forward speed – This enables the pressure and velocity to be found at any point
Second order forces – Mean drift forces: ●
Far field momentum theory
●
Near field pressure-motion integration method
– Full QTF matrix (difference & sum frequency components)
AQWA-LINE provides hydrodynamic coefficients for use in other programs in the AQWA suite
Theory in AQWA LINE
Assumptions – Ideal fluid, irrotational and incompressible – small wave elevation Governing equation for the velocity potential 2
∇ φ = 0
(V = ∇φ )
Body boundary condition (Timman-Newman relations)
∂φ j (r ) ( n1 , n2 , n3 ) = n, = −iω e n j + Um j ∂n ( n4 , n5 , n6 ) = r × n ( m1, m2 , m3 ) = −n ⋅ ∇[∇( −Ux + φ s )] / U = 0, ( m4 , m5 , m6 ) = −n ⋅ ∇[r × ∇(−Ux + φ s )] / U = (0, n3 ,− n2 )
Theory in AQWA LINE ●
Linearized free surface condition
∂φ ω e2 − φ = 0 ∂ z g ●
Sea bed boundary condition
∇φ = 0 when z → −∞ for deep water ∂φ = 0 at z = −d ( sea bed ) for shallow water ∂ z ●
Radiation condition A physical condition to avoid mathematical ambiguity which could result in structure induced waves travelling in the wrong direction
Theory in AQWA LINE
Numerical method ●
Linear superposition of 1st order potential components
φ = [φ I + φ d +
6
∑
x jφ j ] e
j =1
−iω et
,
I for incident wave, d for diffracted wave, j =1,2,…,6 for radiated wave in 6 degrees of freedom, x j: the structure motion for unit wave amplitude
●
Forward speed effect: Encounter frequency ω e = ω (1 −
ω U g
cosθ )
θ : angle between incident wave and forward speed
Theory in AQWA LINE ●
Incident wave potential for finite water depth d ϕ I e
−iω t
=
− igζ cosh[ k ( z + d )]e ik ( x cosθ + y sin θ +α ) e −iω t ω cosh( kd )
in which k is the wave number defined by: ω
●
2
= gk tanh(kd )
Solution for diffracted and radiated wave potentials using pulsating source distribution ϕ ( x, y, z ) =
1
∫∫ σ G ( x, y, z; ξ ,η , ζ ) ds
4π sb
Theory in AQWA LINE ● Green’s function (finite depth water, frequency domain):
G ( x, y, z;ξ ,η , ζ )
=
1
+
1
R R ' ∞
( µ +ν )e
+ 2 pv ∫
0 µ sinh( µ d )
+ 2π i
2
(k −ν 2
2
−µ d
−ν cosh(µ d )
2)
(k −ν )d +ν
cosh µ (ζ + d ) cosh µ ( z + d ) J 0 ( µ r )d µ
cosh k ( z + d ) cosh k (ζ + d ) J 0 (kr )
● Database method used for efficient and accurate evaluation
Minimum input frequency (rad/s): 0.05 * g / d d: water depth
Theory in AQWA LINE The source strength at each panel on the structure surface is assumed constant, calculated by solving the body boundary condition :
∂ϕ ( x, y, z ) ∂G ( x, y, z; ξ ,η , ζ ) 1 1 = − σ ( x, y, z ) + ∫∫ σ ds ∂n ∂n 2 4π sb ●
For the diffraction potential, the induced normal velocity at the structure surface should negate that due to incident potential;
●
For the radiation potentials, the induced normal velocities (in 6 degrees of freedom) should be the same as those due to structure motion.
Theory in AQWA LINE Pressure and 1st order wave force calculation Hydrodynamic pressure on each panel can be calculated from the linearized Bernoulli equation: p
(1)
= − ρ gw − ρ φ t
1st order wave forces are obtained by integrating the pressure over the mean wetted body surface. Froude-Krylov and diffraction force F j (ω e ) = − ∫∫S n j (iω e + U ∂ )(φ I + φ d ) dS b ∂ x ∂ ► Added mass and damping ω e2 M a ij (ω e ) + iω eC ij (ω e ) = ∫∫S ni (iω e + U )φ j dS b ∂ x ► Restoring (hydrodynamic stiffness) K = − ρ g n w dS
►
∫∫S b
ij
i
j
Special cases K 15 = − ρ g ∫∫S n1w5 dS − mg , K 24 = − ρ g ∫∫S n2 w4 dS + mg b
b
Theory in AQWA LINE Second order forces Perturbation approach (ε: small number related to wave amplitude) 1 ( 0) (1) 2 ( 2) p = − ρ φ t − ρ (∇φ ⋅ ∇φ ) + ρ gZ = p + ε p + ε p + ... 2 (0) (1) 2 ( 2) X = ( X , Y , Z ) = X + ε X + ε X + ...
If the 1st order motion/potential/force in the form of N
F ( t ) = ∑ (ai sin ω i t + bi cos ω i t ) (1)
Different freq. components
i =1
then the 2nd order force in ( 2)
F
N N
(t ) = ∑ ∑{ cij sin[(ω i − ω j )t ] + d ij cos[(ω i − ω j )t ] i =1 j =1
+ eij sin[(ω i + ω j )t ] + f ij cos[(ω i + ω j )t ]} mean 2nd order force components ( ω i = ω j ) N ( 2) F = ∑ d ii i =1
Sum freq. components
Theory in AQWA LINE ●
2nd order mean drift f orce calculation ►
Far field solution (momentum conservation method): F strc = − ( 2)
d
ρ V d Ω − ∫∫ p ∫∫∫ dt Ω
= − ρ ∫∫∫ Ω
n
d S
S R
∂V d Ω − ρ ∫∫VV n dS − ∫∫ pn d S ∂t S S R
R
SR: vertical cylindrical boundary surrounding the structure in the flow field with a large radius R, Ω: fluid volume surrounded by SR and the structure surface.
- More accurate - Horizontal force/moment only - Single structure only (or multi-bodies without hydrodynamic interaction)
Theory in AQWA LINE ►
Near field solution (pressure/motion integration method): ( 2)
F strc
= − ∫ 0.5 ρ gζ r 2 n dl + ∫∫ 0.5 ρ ∇ϕ 2 n dS WL
S b
.. ∂ϕ + ∫∫ ρ ( X .∇ )n dS + M s R . . X g ∂t S b
WL:
mean water line along the structure surface; Sb : mean structure wetted surface
- Force/moment in 6 degrees of freedom for each structure - Multi-body hydrodynamic interaction
Theory in AQWA LINE ►
Full Quadratic Transfer Function (QTF) ● ●
Components at both difference and sum frequencies Each with in-phase and out-of- phase parts ( 2)
F
N N
{
[
]
]}
[
(t ) = ∑ ∑ Pij cos − (ω i − ω j )t + (ε i − ε j ) + Pij cos − (ω i + ω j )t + (ε i + ε j ) −
i =1 j =1 N N
{
−
[ (
)
(
+ ∑ ∑ Qij sin − ω i − ω j t + ε i − ε j i =1 j =1
ω1 ω2
…
ωj
….
ωn
+
)] + Qij+ sin[− (ω i + ω j )t + (ε i + ε j )]}
2-D plot of QTF(real)
ω1
Diagonal: Mean drift force/unit wave of ω2
ω2
−
Pij (ω i , ω j ) / ζ iζ j ► AGS
ωi ωn
-> File ->open Graph -> Function/processing -> Data processing -> Wave forces -> Full-coupled QTFs -> 2-D plot ► CQTF card in Options on Deck 0
Theory in AQWA LINE (±)
Pij
= − ∫ 14 ρ gζ i .ζ j cos(ε i ± ε j )n dl
Waterlineintegral
WL
+ ∫∫ 1 4 ρ ∇ϕ i . ∇ϕ j n dS
Bernoulli
S b
∂ϕ j + ∫∫ 2 ρ ( X i .∇ )n dS ∂t S b 1
Acceleration
..
+ M s R . i . Xg j
Momentum
∂φ ( 2) + ∫∫ ρ .n.dS ∂t S b
2nd order potential
Qij±
( )
similar to above
Theory in AQWA LINE ●
Equation of motion in AQWA LINE The response X (RAO) of a structure in waves is calculated by solving the equation of motion in the frequency domain for unit wave amplitude:
[ −ω 2 ( M s + M a (ω )) − iω C (ω ) + K ] X (ω ) = F (ω ) where Ms is structure mass Ma is added mass (frequency dependent) C is damping (frequency dependent) K is hydrostatic stiffness F is wave force (incident and diffracting forces).
Fluid forces on structures Fluid force
Hydrodynamic
Radiation force due to structure motion
Wave exciting force
Ambient pressure (incident wave or Froude-Krylov force)
Effect of structure on waves (Diffraction)
F(ω)
Hydrostatic
=
In-phase (Added Mass)
Ma(ω).x″
Out-of-phase (Radiation damping)
+
C(ω).x′
+
K.x
Modelling (1) ■
using ANSYS ●
Install ANSYS-AQWA interface
(1) copy anstoaqwa.mac to C:\Program Files\Ansys Inc\v110\ANSYS\APDL (2) open C:\Program Files\Ansys Inc\v110\ANSYS\APDL\start110.ans, insert *ABBR, AQWA, ANSTOAQWA ●
run ANSYS Notes: (1) define geometry of wet and dry surface separately; Z-axis upwards; (2) SHELL63 for surface mesh, PIPE59 for tube; (3) check normal direction (blue: outside; pink: inside); (4) Click ‘AQWA’ to output AQWA data file; (5) COG and mass need to be modified.
Modelling (2) ■
Using AGS (wit h AL****.LIN file) ●
Notes on AL****.LIN fi le (see AGS-Help for d etails):
(1) each station starts from lowest point at centre plane; (2) all x-coordinates should be the same on each station; (3) max. 50 points on each station, condense points at high surface change; (4) input stations (max. 100) from stern to bow, only two stations are needed to define a parallel midbody section. ●
run AGS
(1) double click AGS icon on screen; (2) Plots → Select → Lines Plan → File (in Lines Plan Mesh Generation window) → open to find the *.lin file to be opened; (3) Plot Lines (in Lines Plan Mesh Generation window) to show offset curves; (4) input two drafts; COG, mesh size (in Lines Plan Mesh Generation window) , then Generate Mesh; (5) File → Save *.DAT (in Lines Plan Mesh Generation window) to save the generated file. ■
Create model (Approx. Dimensions: 200x40x15, mesh size:6)
Notes: PMAS values in Deck 4 may need to be modified (data\lines\altank.lin)
AQWA File Names Every AQWA file name has three parts: (1) file prefix (two characters) - a code to identify the program al LINE ab LIBRIUM af FER ad DRIFT an NAUT aw WAVE (2) run identifier (up to six characters) - a name to identify the run (3) file extension (three characters) to identify the type of file (eg, .dat) Example:
altank1.dat (input data), abtank1.lis (output list file)
AQWA Global/User defined Systems
AQWA Global Coordinate System (FRA): • • •
the origin lies in the still water plane the positive z axis is vertically upwards Right handed
Z z
W.L.
0
ZCGE(deck7) COG ZLWL(deck2)
User Defined System
a
Right handed, oxy plane shifts vertically from OXY of FRA
X x
Run Stages 1-2
■
● ● ● ●
Run stages 1 – 2 Use the model generated by AGS Be aware of warning messages Check al**.lis file (displacement, mass, stiffness) Check geometry through AGS
Zooming, Rotating, Shade, Showing diff panels, Numbering; Command: omit element -> Plot (to omit all the elements) select element 1 to 10 ->Plot (to display el#1-10 only)
AQWA File Types ● Each AQWA run involves several files. ● The names of the files differ only in the file extension. ASCII
INPUT FILES
.dat input data file (LBDNF) .lin input file for AGS mesh generator .msd input mass distribution for BM/SF ( AGS) .sfm input mass distribution for splitting forces ( AGS) .wht a wave height time history with IWHT in Deck 13 (D) .wvt a wind velocity time history, no card needed (DN) .xft an external force time history acting on a structure no card needed (DN) .mor mooring description file with FILE in Deck 14 (BDNF)
AQWA File Types INPUT/OUTPUT FILES (between stages) .res .hyd .eqp .uss .pot
restart file (binary, LBDNF) hydrodynamics file (binary, L) equilibrium position file (binary, B) source strength file (binary, with LDOP in Deck 0, L) potential file (binary, with LDOP in Deck 0, L)
OUTPUT FILES .mes .lis .pos .plt .pac
output message file ( ASCII, LBDNF) output listing file ( ASCII, LBDNF) output position file (binary, DN) output graphic file (binary, LBDNF) pressures at centroids (binary, L)
.vac
velocities at centroids (binary, L)
See AQWA-Ref 1.3 for details
Input Data (.dat) File ●
ASCII text file containing all the input data necessary for the Stages of Analysis about to be executed.
●
in fixed format and must be entered using a text editor .
●
an editor that indicates the column & line no. of the current cursor position is highly recommended.
Note:
A graphical user interface, which allows interactive data input in a user-friendly environment, is currently under development.
AQWA-LINE Example Data File JOB MESH LINE TITLE MESH FROM LINES PLANS/SCALING OPTIONS REST END RESTART 1 2 *Deck 1 Coordinates -------------01 COOR 01 1 45.000 -45.000 0.000 01 2 22.500 -45.000 0.000 . . . 01 511 146.000 0.000 0.000 . . . END01 999 0.000 0.000 -10.620 *Deck 2 Element Definitions ------------02 ELM1 02SYMX 02SYMY 02QPPL DIFF 0 (1)( 1)( 2)( 12)( 11) . . . . 02QPPL 0 (1)( 1)( 101)( 103)( 3) . . . . END02PMAS 0 (1)( 999)( 1)( 1) 02 FINI
Deck 0: overall administration parameters Analysis Stages
Deck 1: Node coordinates * 999 for PMAS node
Deck 2: Element definitions
Note: Symmetry card (1)
Save pre-processing time
(2)
Save CPU time
(3)
Enlarge capability
(4)
But only for QPPL/TPPL
AQWA-LINE Example Data File (cont) *Deck 3 Material Properties - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 03 MATE END03 1 3.32100E8 * Deck 4 Geometric Properties --------------------------------------------------04 GEOM END04PMAS 1 3.6253E11 0.000000 0.000000 3.4199E11 0.000000 3.5991E11 * Deck 5 Global Data -----------------------------------------------------------05 GLOB 05DPTH 250.0 Deck 5: Defines the UNITS 05DENS 1025.0 for the analysis, see App. A END05ACCG 9.806 * Deck 6 Wave Frequencies and Directions ---------------------------------------06 FDR1 06FREQ 1 6 0.10472 0.15708 0.25133 0.41888 0.52360 0.59840 END06DIRN 1 3 0.00 45.00 90.00 In degrees, ascending order * Deck 7 Analysis Position -----------------------------------------------------07 WFS1 END07ZCGE -10.6200 Deck 6: Analysis position *-----------------------------------------------------------------------------08 NONE * 1 2 3 4 5 6 *234567890123456789012345678901234567890123456789012345678901234567890
Directions in AQWA Directions must be input in ascending sequence (41 max.): ● ● ●
-180 to +180 degrees for a non-symmetric structure; 0 to 180 degrees for a structure symmetric about x axis (SYMX); 0 to 90 degrees for a structure symmetric about both x and y axes (SYMX and SYMY).
y v
θ x
AQWA Data file format JOB MESH LINE TITLE MESH FROM LINES PLANS/SCALING OPTIONS REST END RESTART 1 2 4col 4col5 col5 col 10 cols 10 cols 10 cols 01 COOR 01 1 END01 999
45.000 0.000 Column 21
02 ELM1 02QPPL DIFF
0(1)(
06FREQ
6
1
1)(
0.10472
-45.000 0.000
2)( 0.15708
0.000 -10.620
12)(
11)
0.25133
0.41888
0.52360
Note: Most input data should be typed into the required columns !!! See AQWA-Reference Chapter 4 for details
Listing (.lis) File
● ASCII
text file containing most output data (in text form) from the Stages of Analysis which have just been executed.
●
It can be examined using a text editor .
Restart (.res) File
This is a binary file, ● written by all the AQWA programs, ● contains database associated with all the Stages of analysis which have so far been executed. Examples: If Stages 1 to 4 have been executed, it will contain: (1) model definition (2) hydrodynamic database (3) main analysis parameters
Hydrodynamic (.hyd) File This is a binary file ● created by AQWA-LINE after the diffraction / radiation analysis (Stage 3). ●
contains the hydrodynamic database from the AQWA-LINE run.
Comparison o f AL**.RES and AL **.HYD (after AQWA-LINE Stage 3) restart file(RES)
hydrodynamics file(HYD)
model definition
Used for
hydrodynamic database
hydrodynamic database
further run AGS regenerate .HYD file (RDDB)
further run manipulate ( ALDB in Deck 0, FILE in Deck 6 )
Position Files (.pos and .eqp)
Both are binary files. AB***.eqp file: ● created by AQWA LIBRIUM ● stores the equilibrium positions of a system of structures. ● can be read in by FDN as start position (with an option RDEP in Deck 0). A****.pos file: ● created during a time domain analysis by DN ● stores the positions, velocities, etc of a system of structures for every time step.
AGS Plot File (.plt) This is a binary file ●
created during a calculation stage (Stage 3 or 5)
●
contains either: – time history of forces and motions (DN) – positions and forces during iteration towards equilibrium (B) – forces and responses as a function of frequency (LF)
●
for AGS use
AQWA Restart Stages Stages: Categorize analys is procedures ● Can be run individually/in combination ● Data transfer through stages
Stage 1
Model Definition,
Decks 1 to 5
Stage 2
Hydrodynamic Database,
Decks 6 to 8
Stage 3
Diffraction/Radiation Analysis* (L)
Stage 4
Main Analysis Parameters Decks 9 to 20 (BDNF)
Stage 5
Main Analysis* (BFDN)
* Calculation Stages only
Stage 1 Decks: Categorize input data Deck 1
COOR
Node Coordinates Structure Number
Deck 2
ELM*
Element Definitions
Deck 3
MATE
Material Properties
Deck 4
GEOM
Geometric Properties
Deck 5
GLOB
Global Constants
Depth, G, ρ(water): UNITS
Deck Header (compulsory)
Stage 2 Deck 6
FDR*
Regular Wave Definitions (1) frequencies and directions (2) copy, merge, edit the existing hydrodynamic database.
Deck 7
WFS*
Hydrodynamic Properties (wave freq. range) Hydrostatic Properties (stiffness and buoyancy) Analysis Position (ZCGE, can be replace by ZLWL in Deck2)
Deck 8
DRC*
Drift Force Coefficients
* Structure Number
Note:
The hydrodynamic properties input in Stage 2 are used to modify or replace those calculated by AQWA-LINE (Stage 3)
Stage 3 This is the main AQWA-LINE analysis and is a calculation stage only.
Note:
The hydrodynamic properties input in Stage 2 are used to modify or replace those calculated by AQWA-LINE (Stage 3)
Stage 4 Deck 9
DRM*
Drift Motion Parameters (drift freq.) (drag, added mass/damping)
Deck 10 HLD*
Hull Drag Coefficients (1) current/wind drag coefficients (2) external force by user_force.dll (with option FDLL)
Deck 11 ENVR
Environmental Parameters (wind and current)
Deck 12 CONS
Constraints (deactivate/constraint) (deactivate/constraint)
Deck 13 SPEC
Spectral Parameters (wave, wind spectrum / time history) Regular Wave Parameters (N ( N)
WAVE Deck 14 MOOR
* Structure Number
Mooring Line Definitions (mooring, fender, pulley, winch)
Stage 4 (cont) Deck 15
STRT
Starting Conditions (BFDN (BFDN))
Deck 16
TINT LMTS
Time Integration Parameters (D,N ( D,N)) Iteration Parameters (B ( B)
Deck 17
HYDC
Additional Hydrodynamic Hydrodynamic Parameters for Tubes (scaling & slamming factors , N)
Deck 18
PROP
Printing Options (for additional information)
Deck 19/20 NONE
Reserved for future use
Stage 5 This is the main solution stage and is a calculation stage only.
Deck 21
ENLD
Element and nodal loads (on TUBEs, Stage 6, 6, DN DN))
AQWA Element Types Elements are defined in AQWA Deck 2: QPPL : TPPL : TUBE : STUB : PMAS: PBOY: FPNT : DISC :
Quadrilateral panel (diffracting or non-diffracting) Triangular panel (diffracting or non-diffracting) Tube element (circular cross section) Slender tube element (non-circular cross section allowed) Point mass and inertia Point buoyancy Field point (for wave surface calculation) Circular disc with no thickness.
Notes: (1) DIFF is needed for diffracting QPPL and TPPL elements; (2) ILID/VLID for defining external diffracting elements;
Definition of other elements OB MESH NAUT TI TLE TUBES AND DI SCS OPTI ONS REST END RESTART 1 5 01 COOR 010001 10. 0 0. 000 010002 10. 0 0. 000 010003 10. 0 0. 000 END01 999 0. 00 0. 000 02 ELM1 02TUBE ( 2) ( 1, 1) ( 2, 1) ( 1) ( 1) 02DI SC ( 1) ( 3) ( 2) ( 3) 02DI SC ( 1) ( 1) ( 2) ( 3) END02PMAS ( 1) ( 999) ( 2) ( 2) 03 MATE 03 1 1. 00E- 6 END03 2 4025. 00 04 GEOM 04TUBE 1 1. 00 0. 05 04CONT 0. 75 1. 00 04DI SC 3 1. 20 04CONT 1. 14 1. 00 END04PMAS 2 6000. 00 0. 00 05 GLOB 05DPTH 500. 0 05DENS 1025. 0 END05ACCG 9. 806 ... ... 20 NONE
Program name
2. 000 0. 000 - 3. 000 - 0. 500
Define TUBE element See APP H
Define DISC elements
0. 00
0. 00
6000. 00
0. 0
4000. 00
Warnings in AQWA-LINE General warnings requirements
reason
No. of elements ≤ 8000 diff. 12000 total
solution time
Normals point out
modelling convention
No gaps
force balance
Facets cannot cut surface
solution requirement
Dimensions < KR
good practice
Warnings in AQWA-LINE Stage #1 checks (Geometric properties) Area ratio of adjacent elements < 3 Aspect ratio > ⅓, (c=1, for QPPL; c=2.3, for TPPL)
Element centres at least one facet radius apart Shape factor (parameter for the regularity of panel) < 0.2 – warning < 0.02 – fatal error Note: See AQWA-Course Appendix 3 for detail
AR
r f
area longest side
area
2
.C
Warnings in AQWA-LINE Stage #2 checks (hydrodynamic) Longest side < 1/7 wavelength Fatal error if more than 5% fail Distance above sea bed must be > 0.5.r f (use non-diffraction elements otherwise)
Warning if nodes not connected to another element (for pressure contour, NPPP in Deck 0 overrides warning)
Minimum wave frequency (rad/s) > 0.05 * g / d
AQWA-LINE run
Run stages 1 - 3 ● use generated model (altank1.dat altank2.dat) ● add LDOP, GOON option, check mass and inertia moments ● discuss .dat file ● discuss .lis file ● AGS to show results and functions
Useful Options in AQWA-LINE (1)
Following option cards can be used in Deck 0: DATA
check input data (equivalent to Stages 1-2, LBDFN)
GOON
ignore non-fatal modelling rule violations (L)
REST
define restart stages (LBDFN)
LDOP
LOad OutPut - outputs .POT and .USS files needed for pressure calculations (e.g pressure plots, SF/BM) (L)
PRCE
PRint Card Echo for Decks 1 – 5 (LBDFN)
PPEL
Print Properties for each Element (LBDFN)
Useful Options in AQWA-LINE (2)
NPPP No Pressure Post-Processing - prevents nodal connectivity warnings (L) CRNM Re-calculate RAOs (LF) NRNM Calculate nodal RAOs(L) NQTF Use near-field solution for drift force coefficients (L) CQTF Calculate QTF matrix (L)
AQWA-LINE Post Processing Wave surface contour pl ots
Note:
● LDOP card in al*.dat file ● run AGS
(1) double-click AGS icon on screen; (2) File → Open to input al*.res file; (3) Plots to show the model; (4) Wave Contours to show or calculate wave contour if not existing; (5) choose required waves (dir. freq. in Wave Surface Contours window); (6) tick Cycle to animate; (7) point Cursor to a specified location to show the numerical value at that point .
AQWA-LINE Post Processing Air Gap
Note: ● LDOP card in al*.dat file ● run AGS (1) double-click AGS icon on screen; (2) File → Open to input al*.res file; (3) Plots to show the model; (4) Wave Contours to show or calculate wave contour if not existing; (5) choose required waves (dir. freq. amp. in Wave Surface Contours window); (6) RAO Motion → Ref. Height(Z) above SWL → Include RAO motion; (7) tick Cycle to animate; (8) point Cursor to a specified location to show the numerical value at that point.
AQWA-LINE Post Processing Pressure Contour s
Note: ● run AGS
(1) double-click AGS icon on screen; (2) File → Open to input al*.res file; (3) Plots to show the model; (4) Select (in Model Visualization window) → Pressure Contours; (5) choose required waves (dir. freq. in Pressure Contours window) → Time=t to animate; (6) Select (in Model Visualization window) →Sequence (7) Start Sequence (in Define Sequence window) → Stop Sequence → Record Every ● save sequence fil es if requir ed (8) Hardcopy → Output .bmp on playback → Rewind << → Play > → BMP FILE DUMP (yes) (9) Using a software to convert .BMP file into .gif file which may be replayed by internet explorer or .avi file which can be insert into Powerpoint
AQWA-LINE Post Processing Diffracted Wave Surface
Note: ● LDOP card in al*.dat file ● run AGS
(1) double-click AGS icon on screen; (2) File → Open to input al*.res file; (3) Plots to show the model; (4) Select (in Model Visualization window) → Pressure Contours; (5) choose required waves (dir. freq. in Pressure Contours window) → Time=t to animate; (6) View Angle (in Pressure Contours window) →Choose view angle (in Contour View Angle window) (7) Option (in Pressure Contours window) →Wave Amplitude & Diffracted Wave Surface (in Hull Contours / Diffracted Wave Option window); (8) Select (in Model Visualization window) →Sequence (9) Start Sequence (in Define Sequence window) → Stop Sequence → Record Every
AQWA Database Manipulation Reason: without re-running the full AQWA-LINE analysis, ● add in additional nodes, elements, damping etc; ● combine several databases into one.
Example 1: modify nodes & elements of single structure (1) copy existing data file ALTANK2.DAT to ALTANK3.DAT; (2) add new nodes, (non-diffracting) elements (3) delete all wave frequency and direction cards in Deck 6, change this deck into: 06 FDR1 06FI LE ALTANK2. HYD Structure number in 06CSTR 1 ALTANK2 END06CPDB (4) run AQWA-LINE for ALTANK3.DAT (which takes a few seconds).
AQWA Database Manipulation (cont.1) Example 2: modify damping of single structure
(1) copy existing data file ALTANK3.DAT to ALTANK4.DAT; (2) delete all wave frequency and direction cards in Deck 6, change this deck into: Structure number in AL2 06 FDR1 06FI LE ALTANK2. HYD Structure number in AL1 06CSTR 1 END06CPDB (3) add new damping coefficients (CRNM option needed for RAO recalculation); 07 WFS1 07ZCGE END07FI DD
0. 0000
New card to add damping Columns 51-60 for roll damping
1. 000E09
(4) run AQWA-LINE for ALTANK4.DAT (which takes a few seconds). → Compare the RAOs in ALTANK3 and ALTANK4 using AGS (merging curves)
AQWA Database Manipulation (cont.2)
Multiple structure database combination (1) merging without hydrodynamic interaction ● run each model (AL**1.dat and AL**2) individually; ● include all structure definitions in the new AL**3.DAT file ● add corresponding file name in DECK 6 FILE card in AL**3.DAT for each structure (2) modify nodes etc for hydrodynamic interaction model Similar to Example 2, but in Deck 6 only the first structure needs to be input for each interaction group.
NOTE: When CQTF is used, manipulation can been done in version 12.0 thereafter
Equilibrium position, Static and Dynamic stabilit y
- Complex ship/ offshore structure system; - Various mooring, fender, pulley, winch, constraints configuration; - Equilibrium estimation under wave, wind and current combination; - Database approach for static catenary mooring line; - Finite element approach for dynamic cable (drag force); - Iteration approach for determining equilibrium position; - Calculate the eigenvalues of linearised stiffness matrix to obtain static stability; - Eigenvalues of the impedance matrix to give dynamic stability. - Series of wave spectrums and mooring configurations
Theory in AQWA LIBRIUM ● Equation for determining static equilibrium position: X j +1 = X j + K − ( X j ) F ( X j ) 1
K is the stiffness matrix of the system, F is the force matrix. The program iterates until ∆X=|X j+1-X j| is less than a defined tolerance
● Static stability K X − λ X
=0
Eigenvalue λ (<0, unstable; =0, neutral; >0, stable)
● Dynamic stability
M −1C I (from
M
−1K X 0
X + λ = 0, X X
+ C X + K X M X
= 0, X = eλ t , λ = f + ig )
Eigenvalue (f<0, stable; f>0 and g=0, unstable; f>0 and g ≠0, fishtailing)
Analysis Procedure A common method of analysis (1) run Stages 1 to 3 in AQWA-LINE (2) run Stages 4 to 5 in another program, say, AQWA-LIBRIUM. Example: Step 1: AQWA-LINE run (Restart 1 to 3)
Step 2: AQWA-LIBRIUM run (Restart 4 to 5)
Input Files
Output Files
Input Files
altest.dat
altest.lis altest.res altest.hyd altest.plt
abtest.dat altest.res
Output Files abtest.lis abtest.res abtest.eqp Input in RESTART card starting from Column 21
Analysis Procedure (cont) Stage 4 in AQWA-LIBRIUM – model definition – hydrodynamic database – main analysis parameters
restart file restart file input data file
Note: ● Decks 1 to 8 data is read from the restart file ● Decks 9 to 20 are required in the input data file (Decks 1 to 8 must be omitted if restart from Stage 4).
Stage 5 in AQWA-LIBRIUM (Main analysis, no extra input)
AQWA-LIBRIUM J OB TEST LI BR TI TLE OPTI ONS REST END RESTART 4 5 09 NONE 10 NONE 11 NONE 12 NONE 13 SPEC 13SPDN END13PSMZ 14 MOOR 14LI NE 1 14LI NE 1 14LI NE 1 END14LI NE 1 15 STRT END15POS1 1 16 NONE 17 NONE 18 NONE 19 NONE 20 NONE
(Example 1)
JOB card
FALTI NSEN BOX - MODEL 1
Read database
ALBOXM
Deck 9: drift motion parameters; Deck 10: wind and current drag; Deck 12: constraints; Deck 11: environment; Deck 13: spectrum 315. 0 0. 300 501 502 503 504 1
0 0 0 0
2. 000
4. 000
511 512 513 514
1. 4715E6 1. 4715E6 1. 4715E6 1. 4715E6
100. 0 100. 0 100. 0 100. 0
0. 0
0. 0
1. 5
8. 000
Deck 14: Mooring system NB new nodes needed 0. 0
0. 0
Deck 15: Initial position of COG in global frame
Drag in AQWA (deck 10) (1) Current and Wind Force Coefficients
DIRN SYMX CUFX WIFX etc
Dir1
DirN
Θ1 …. ΘN (optional) (optional)
Dir1 Dir1
DirN DirN
C1 …. CN C1 …. CN
Direction sequence no. If DIRN is not present in Deck 10, the directions are those defined on the DIRN cards in Deck 6
Dir: direction number – directions default to LINE wave directions; C1: Drag Force Coefficients For relative current velocit y V in direction
force in X direction force in Y direction yaw moment
= CUFX ϕ.V2 = CUFY ϕ.V2 = CURZϕ.V2
Drag in AQWA (deck 10) (cont 1) (2) Moris on Drag Coefficients (for ship hul l)
MDIN
Nrow
Ncol
C1 …. C6
Nrow: Row number in drag matrix Ncol: Column number in drag matrix C1 – C6: Drag Force Coefficients C 11 C 21 C 31 DragForce = C 41 C 51 C 61
C 12
C 13
C 14
C 15
C 16 x. x
C 22
C 23
C 24
C 25
C 32
C 33
C 34
C 35
C 42
C 43
C 44
C 45
C 26 y. y C 36 z. z . . ϕ C 46 ϕ
C 52
C 53
C 54
C 55
C 62
C 63
C 64
C 65
.θ C 56 ϑ
C 66 ψ .ψ
Useful options in AQWA LIBRIUM
STAT
STATic stability only In JOB card Deck 0
DYNA
DYNAmic stability only
PBIS
Print Both Iteration Steps (prints full results at each step)
PRAF
Print all freedoms (in spite of DACF cards on DECK12)
In OPTIONS card Deck 0
AQWA-LIBRIUM Example 2 (ABTANK4) JOB card
JOB TANK LIBR TITLE
SINGLE TANKER WITH MOORING
Read database
OPTIONS REST PBIS END RESTART
4
5
ALTANK4
09
NONE
10
HLD1
Direction sequence no. If DIRN is not present in Deck 10, the directions are those defined on the DIRN cards in Deck 6
10SYMX 10DIRN 10DIRN 10WIFX
1 6 1
5
0.0
10
100.00
5
1.460E3
20.00 120.00 1.692E3
40.00
60.0
140.00
160.0
1.685E3
1.175E3
80.00 180.00 3.745E2
10WIFX
6
10 -3.427E2 -9.839E2 -1.520E3 -1.692E3 -1.794E3
10CUFX
1
5
0.505E5
0.572E5
0.532E5
0.344E5
0.172E5
6
10
0.808E7
0.220E8
0.191E8
0.103E8
0.00000
. . . END10CURZ
AQWA-LIBRIUM Example 2 (ABTANK4) 11 NONE 12 NONE 13 SPEC 13SPDN 13CURR 13WIND END13PSMZ
315.0 1.00 315.0 25.00 315.0 0.3000 2.0000
4.000
8.000
Deck 11:envirn.; Deck 12:constraints; Deck13: spectrum
AQWA-LIBRIUM Example 2 (ABTANK4) 14 MOOR 14LINE 1 5001 0 6001 14LINE 1 5002 0 6002 14LINE 1 5003 0 6003 14LINE 1 5004 0 6004 END14 15 STRT 15POS1 100.00 END 16 LMTS END16MXNI 200 17 NONE 18 NONE 19 NONE 20 NONE
Deck 14: Mooring system 1.50E6 1.50E6 1.50E6 1.50E6
142.0 142.0 142.0 142.0 Deck 15: Initial position
0.000
0.000
0.000
0.000
0.000
Deck 16: Iterative parameters
AGS online calculation Mini-Librium
Note:
run AGS (1) double-click AGS icon on screen; (2) File → Open to input al*.res file; (3) Plots to show the model; (4) Move Structure (in Model Visualization window) if needed; (5) MINI-LIBRIUM (in Model Visualization window); (6) Iterations (in MINI-LIBRIUM window to choose the iteration step number); (7) Equilibrate (till converged)
AGS online calculation Static stabilit y
Note:
run AGS (1) Double-click AGS icon on screen; (2) File → Open to input al*.res file; (3) Plots to show the model; (4) Run -> AQWA-LIBRIUM (5) Display (in AQWA-LIBRIUM Run Monitor window) -> Static Stability Modes; (6) Click Mode# (in Static Stability Displacement Modes window to animate the mode).
Mooring Lines in AQWA (deck 14) Mooring lines can be defined in (BDNF) Commonly used mooring typ es:
(1) LINE: Linear elastic line (weightless) 14LINE
Ns1
Nd1
Ns2
Nd2
K
L
(Ns1, Ns2: structure numbers; Nd1, Nd2: node numbers; K: stiffness; L: unstretched length) (2) POLY: Polynomial elastic line (weightless) 14POLY 14NLIN
K1 Ns1
K2 Nd1
K3 Ns2
K4 K5 Nd2 (Ts)
L
(Fw)
(Fp)
(K1, .., K5: stiffness; Ts: winch tension; Fw: winch winding in friction factor; Fp: winch paying out friction factor; Ts, Fw and Fp are only needed when the POLY line is used as a winch )
Mooring Lines in AQWA (deck 14) (cont.1) (3) COMP/ECAT: Composite elastic catenary (with weight) 14COMP 14ECAT 14ECAT 14ECAT 14NLI N
Nz, Nx Ne Zmin, Zmax Slope
Nz
Ns1
Nx
Nd1
Ne
Ns2
Zmi n M1 M2 M3
Zmax A1 A2 A3
Sl ope EA1 EA2 EA3
Tmax1 Tmax2 Tmax3
L1 L2 L3
Nd2
Start from anchor point
-- number of database points within z and x ranges. -- number of ECAT in this COMP line. -- Z range (measured from the anchor) for the attachment node. -- sea bed slope (in degrees; positive for slope going up from anchor towards attachment point). M1,M2,M3 -- mass per unit length for ECAT 1,2,3. A1,A2,A3 -- equivalent cross section area. EA1,EA2,EA3-- Young’s modulus x area. Tmax1-3 -- maximum tension. L1,L2,L3 -- length of ECAT 1,2,3. Ns,Nd -- structure number and node number (Ns1: fairlead structure).
Moorings database
XRMIN
XRMAX
ZRMAX
ZRMIN
Max. tension point Slack point
AQWA-LIBRIUM Example 3 J OB MESH LI BR TI TLE MESH FROM LI NES PLANS/ SCALI NG OPTI ONS REST PBI S LSTF END Stages RESTART 1 5 01 COOR 015001 015002 015003 015004
01 1 01 2 01 3 . . . 01 501 01 511 . . . END01 999 02 ELM1 02SYMX 02SYMY 02QPPL DI FF 02QPPL DI FF 02QPPL DI FF 02QPPL . . . . END02PMAS 02 FI NI
1700. 200. 200. -1500.
0. -1500. 1500. 0.
-300 -300 -300 -300
45. 000 22. 500 0. 000
- 45. 000 - 45. 000 - 45. 000
0. 000 0. 000 0. 000
45. 000 146. 000
0. 000 0. 000
0. 000 0. 000
0. 000
0 0 0 0
0. 000
( 1) ( ( 1) ( ( 1) ( ( 1) (
1) ( 11) ( 21) ( 1) (
2) ( 12) ( 22) ( 5) (
0 ( 1) (
999) (
1) (
- 10. 620
12) ( 22) ( 32) ( 105) ( 1)
11) 21) 31) 101)
JOB card 1-5, if Deck 1-8 include
Nodes for anchor points
AQWA-LIBRIUM Example 3 (cont.) 03 MATE END03 1 3. 32100E8 04 GEOM END04PMAS 1 3. 6253E11 05 GLOB 05DPTH 250. 0 05DENS 1025. 0 END05ACCG 9. 806 06 FDR1 06FILE 06CSTR 1 END06CPDB
07 WFS1 07ZCGE END07FI DD 08 NONE 09 DRM1 09FI DD END09 10 HLD1 10WI FX 1 10WI FX 6 10WI FY 1 10WI FY 6 10WI RZ 1 10WI RZ 6
0. 000000
0. 000000
0. 000000
0. 000000 3. 4199E11
0. 000000 3. 5991E11
Read database from AQWA-LINE
ALBOXM.HYD
- 2. 0000 1. 000E09
5 9 5 9 5 9
1. 0373E5
1. 5702E6
1. 0E07
4. 0E09
2. 0E10
1. 460E3 - 3. 427E2 0. 000E0 6. 293E3 2. 475E2 1. 167E5
1. 692E3 - 9. 839E2 1. 803E3 5. 618E3 - 1. 407E5 1. 842E5
1. 685E3 - 1. 520E3 3. 623E3 4. 103E3 - 1. 689E5 1. 559E5
1. 175E3 - 1. 692E3 5. 168E3 0. 0 - 1. 068E5 0. 0
3. 745E2 6. 093E3 - 1. 167E4
5. 000E09
AQWA-LIBRIUM Example 3 (cont.) 10CUFX 1 10CUFX 6 10CUFY 1 10CUFY 6 10CURZ 1 END10CURZ 6 11 NONE 12 NONE 13 SPEC 13SPDN 13CURR 13WI ND END13PSMZ 14 MOOR 14COMP 14ECAT 14ECAT 14ECAT
20
14NLI N 1 14NLI N 1 14NLI N 1 END14NLI N 1 15 STRT END15POS1
5 9 5 9 5 9
0. 505E5 - 0. 160E5 0. 000E0 0. 550E6 0. 000E0 0. 808E7
315. 0 1. 00 10. 00 0. 3000 30
3
3201 3201 3201
0 5001 0 5002 0 5003
3201
0 5004
213. 000
0. 572E5 - 0. 295E5 0. 207E6 0. 478E6 - 0. 118E8 0. 220E8
0. 532E5 - 0. 451E5 0. 394E6 0. 382E6 - 0. 213E8 0. 191E8
0. 344E5 - 0. 466E5 0. 486E6 0. 0 - 0. 239E8 0. 0
0. 172E5 0. 542E6 - 0. 118E8
Composite catenary (start from anchor section)
315. 0 315. 0 2. 0000
4. 000
8. 000
280. 150.00 120.00 170.00
300. 0.00 0.00 0.00
6.0000E8 9.0000E8 6.0000E8
- 213. 000
Fairlead first, anchor point second
- 2. 00
0. 000
7.500E6 7.500E6 7.500E6
0. 000
500.0 500.0 700.0
144. 0
AQWA-LIBRIUM Example 3 (cont.)
16
LMTS
16MXNI 16MMVE END16MERR
17 18 19 20
NONE NONE NONE NONE
250 1 1
1.5 0.5
1.5 0.5
1.5 0.5
Iteration controls
1.5 0.5
1.5 0.5
1.5 0.5
Mooring Lines in AQWA (deck 14) (cont.2) AQWA Cable Dynamics (only applicable to COMP/ECAT): (abtank6) 14 MOOR 14COMP 20 30 14ECAT 14ECAH 14ECAT 14ECAT 14ECAH 14NLID 1 5001 14NLID 1 5002 14NLID 1 5003 END14NLID 1 5004
3
0 6001 0 6002 0 6003 0 6004
490. 150.00 1.00 120.00 170.00 1.00
510. 0.010 6.0000E8 7.500E6 0.75 0.10 0.010 9.0000E8 7.500E6 0.010 6.0000E8 7.500E6 1.00 0.15
400.0 500.0 700.0
Catenary hydrodynamic coefficient
Similar to NLIN
Mooring Lines in AQWA (deck 14) (cont.3)
Fenders 14POLY 14FEND 14FLIN Type
in which K1 – K5 Size Kf Kc Type Ns1 Nd1, Nd2 Ns2 Nd3, Nd4
K1 Si ze Ns1 Nd1
K2 Nd2
Ns2
K3 Kf Nd3
K4
K5 Kc
Nd4
-- non-linear stiffness coefficients -- uncompressed size of fender (normal direction) -- tangential friction coefficient -- normal damping coefficient -- 1 = fixed fender, 2 = floating fender -- Structure to which fender is nominally attached -- Nodes defining attachment point and contact plane on 1 st structure -- Structure which fender contacts -- Nodes defining attachment point and contact plane on 2 nd structure
Note: Be aware of valid range of force – extension/compression relationship 2
3
4
T = K 1∆ X + K 2 (∆ X ) + K 3 (∆ X ) + K 4 (∆ X ) + K 5 ( ∆X )
5
Mooring Lines in AQWA (deck 14) (cont.4) Other cards in deck 14 (refer to AQWA Reference Manual for more details) BUOY/CLMP A buoy or clump weight TELM:
Tether element. (for installed or towed stiff tethers)
WNCH:
Constant tension winch line
FORC:
A constant force in a constant direction.
LINE/PULY:
Linear elastic pulley line.
LE2D:
User defined tension/extension data base.
SWIR:
Steel wire with non-linear stiffness.
DWT0/LNDW A line winding in or out on a winch LBRK:
Line breaking.
FILE:
Read in mooring definition from an external file *.MOR.
With weight (COMP/ECAT,NLIN,NLID)
Without weight (LINE,NLIN, FEND/FLIN)
AQWA Printing Options (deck 18) ● ●
by default, part of results output to limit file size additional data can be output by Deck 18 commands ALLM:
Output the velocity, acceleration and position of a user specified node defined in the NODE card.
NODE:
Output the motion of a user specified node or the relative motion between two user specified nodes.
PREV:
Write into *.LIS file every N time steps to reduce the size
PRNT:
Print a force not in the output by default (See AQWA-ref 4.18.6)
PTEN:
Output mooring tension, anchor uplift, laid length etc for mooring line.
ZRON:
Output the z position of a node relative to the incident wave surface .
PMST:
Output mooring sectional tensions for cable dynamic case
AQWA FER - introduction Principally for calculating the significant response of amplitues in irregular waves. Frequency domain program Linearised stiffness matrix / damping to obtain the transfer function and response spectrum Simple, inexpensive approach to make systematic parameter study Series of wave spectrums and mooring configurations
Theory in AQWA FER
Response spectrum in irregular waves
S x x (ω ) = ∑ [mod ( H ij (ω ) F j (ω ))]2 S (ω ) i i j
Sxixi(ω): response spectrum in i-th degree of freedom, Hij (ω) : receptance matrix defined as:
H ij (ω ) = [ −ω 2 ( M s + M a (ω )) − iω C (ω ) + K ]−1 F j(ω):
S(ω):
frequency dependent force (in j-th degree of freedom) on the structure the wave spectrum
Linearisation in FER ► Stiffness: stiffness (hydrostatic, mooring etc.) at the initial position,
(= the static equilibrium position with RDEP option) ► Damping:
cable drag is linearised using the r.m.s. velocity, when NLID used FD = (CD. |Vrms|) .V wind drag is linearised, 1st order hydrodynamic damping any other input damping (fender, constraints) ► Forces:
1st and 2nd order wave forces
Useful options in AQWA FER
JOB options (JOB card) DRFT DRiFT frequency only WFRQ Wave FReQuency only
ANALYSIS options RDEP FQTF
(OPTIONS card) ReaD Equilibrium Position Full diff freq. QTF to be used
Printing options PRRI GLAM
(OPTIONS card) Printing RAOS at spectrum integration points Output significant motions in GLOBAL axis
AQWA-FER
Example 1
For AQWA-FER run J OB TANK FER TI TLE SI NGLE TANKER WI TH CABLE DYNAMI C Read equilibrium position OPTI ONS REST RDEP END RESTART 4 5 ABTANK6 fro m ABTANK6 database 09 DRM1 *2345678901234567890123456789012345678901234567890123456789012345678901234567890 09FI DA 1. 0373E6 1. 5702E7 1. 0E12 1. 0E15 1. 0E15 2. 2564E11 09FI DD 1. 80E5 1. 80E6 1. 0E10 1. 0E13 1. 0E13 1. 00E10 END09 10 HLD1 10WI FX 1 5 1. 460E3 1. 692E3 1. 685E3 1. 175E3 3. 745E2 . . . 10CURZ 1 5 0. 000E0 - 0. 118E8 - 0. 213E8 - 0. 239E8 - 0. 118E8 END10CURZ 6 10 0. 808E7 0. 220E8 0. 191E8 0. 103E8 0. 00000 11 NONE 12 NONE 13 SPEC 13SPDN 315. 0 Optional fr eq. independent 13CURR 1. 00 315. 0 added mass/damping 13WI ND 25. 00 315. 0 END13PSMZ 0. 3000 2. 0000 4. 000 8. 000
AQWA-FER Example (cont.) 14 MOOR 14COMP 20 14ECAT 14ECAH 14ECAT 14ECAT 14NLI D 1 14NLI D 1 14NLI D 1 END14NLI D 1 15 NONE * 15 STRT * 15POS1 *END 16 NONE 17 NONE 18 NONE 19 NONE 20 NONE
30
5001 5002 5003 5004
3
0 0 0 0
490. 150. 00 1. 00 120. 00 170. 00
510. 0. 010 0. 010 0. 010
6. 0000E8 1. 33 9. 0000E8 6. 0000E8
0. 000
0. 000
0. 000
7. 500E6 0. 10 7. 500E6 7. 500E6
400. 0 500. 0 700. 0
6001 6002 6003 6004
100. 00
0. 000
0. 000
Not needed due to RDEP
AQWA NAUT & DRIFT - introduction
■ AQWA-NAUT and DRIFT are time-domain simulation
programs ■ For a series of time-steps they:
calculate the total force on the structure calculate the acceleration find the new position of the structure repeat ■ A two stage predictor/corrector integration scheme is used
Theory in AQWA NAUT and DRIFT Equation of motion in time domain ..
M s X (t ) = F (t )
F(t): the total force on the structure, including incident wave force diffraction force ● ● mooring force drift force ● ● drag force constraint force, etc ● ● radiation force ● Convolution integration form:
t
(t ) + K X (t ) + h(t − τ ) X (τ )d τ = [M s + M a (∞)] X ∫ 0
F 1 (t )
Simulation of Irregular Waves Wave spectrum treatment: ● split into N sections of equal area ● define N wavelets with frequency at the centroid of the section
(max.200). ● the wavelets are added together with random phase angles N
ζ ( x, y, t ) = ∑ ai cos(k i x cosθ + k i y sin θ − ω it + ε i ), ai = 2 S (ω i ) ∆ω i i =1
S(ω) Wavelet: equal areas
.
ω
Comparison of DRIFT v. NAUT
AQWA-DRIFT
AQWA-NAUT
Irregular waves only
Regular or Irregular waves
Linear hydrostatic stiffness
Non-linear hydrostatics / Froude-Krylov force
2nd order drift coefficients
2nd order incident wave Omits drift forces (but some 2nd order effects)
Mean wetted surface
Instantaneous wetted surface
AQWA-DRIFT
Example 1
Job card for DRIFT r un
J OB TAN TANK DRI F WFRQ TI TLE SI NGLE TAN TANKER KER WI TH CABLE DYNA YNAMI C Drift & w ave freq. motions OPTI PT I ONS REST PBI S CONV RD RDEP END RESTART RESTART 4 5 ABTANK6 ABTANK6 09 DRM1 * 23456789012345678901234 23456789012345678901234567890123456789 56789012345678901234567890123 01234567890123456789012345678 456789012345678901234567890 901234567890 09FI 09FI DA 1. 0373 0373E6 E6 1. 5702 5702E7 E7 1. 0E12 0E12 1. 0E15 0E15 1. 0E15 0E15 2. 2564 2564E1 E11 1 09FI 09FI DD 1. 80E5 80E5 1. 80E6 80E6 1. 0E10 0E10 1. 0E13 0E13 1. 0E13 0E13 1. 00E1 00E10 0 END09 10 HLD1 10W 10WI FX 1 5 1. 460E 460E3 3 1. 692E 692E3 3 1. 685E 685E3 3 1. 175E 175E3 3 3. 745E 745E2 2 . . . END END10CU 10CURZ 6 11 NONE 12 NONE 13 SPEC 13SPDN 13SPDN 13CU 13CURR 13WI ND END END13PSMZ
10
0. 808E7 808E7
315. 0 1. 00 25. 00 0. 3000 3000
0. 220E8 220E8
0. 191E8 191E8
0. 103E8 103E8
0. 00000 00000
Convolution method for radiation force 315. 0 315. 0 2. 0000 0000
4. 000
8. 000
Print at both integration stages.
AQWA-DRIFT Example (cont.)
14 MOOR 14COMP 20 30 14EC 14ECAT 14EC 14ECAH 14EC 14ECAT 14EC 14ECAT 14NLI 14NLI D 1 14NLI 14NLI D 1 14NLI 14NLI D 1 END END14NL 14NL I D 1 15 NONE 16 TI NT END END16TI ME 2000 17 NONE 18 PROP END18PREV 5 19 NONE 20 NONE
3
5001 5002 5003 5004
490. 150. 150. 00 1. 00 120. 120. 00 170. 170. 00 0 6001 0 6002 0 6003 0 6004
0. 5
510. 0. 010
6. 0000E 0000E8 8
0. 010 0. 010
9. 0000E 0000E8 8 6. 0000E 0000E8 8
7. 500E6 500E6 1. 33 7. 500E6 500E6 7. 500E6 500E6
400. 400. 0 0. 10 500. 500. 0 700. 700. 0
Defin De fin e no. and value of ti me steps
Define printing options
Useful options in AQWA DRIFT
WFRQ
Include Wave FReQency (default is Drift frequency only)
CONV
Use CONVolution
PBIS RDEP FQTF
Print Both Integration Steps ReaD Equilibrium Position Use diff freq. full QTF matrix (CQTF ( CQTF should be in LINE LINE))
AQWA-NAUT
Example 1
J OB MESH NAUT Job card for NAUT run TI TLE MESH FROM LI NES PLANS/ SCALI NG OPTI ONS REST PBI S END Default regular wave RESTART 1 5 analysis 01 COOR 015001 1700. 0. - 300 01 101 0. 001 0. 000 0. 000 . . . . END01 999 88. 025 0. 000 10. 000 02 ELM1 02SYMX 02QPPL DI FF 1 ( 1) ( 202) ( 201) ( 101) ( 102) . . . . END02PMAS 0 ( 1) ( 999) ( 1) ( 1) 02 FI NI 03 MATE END03 1 84062048. 04 GEOM END04PMAS 1 1. 6812E10 0. 000000 0. 000000 3. 7659E11 0. 000000 3. 7659E11 05 GLOB 05DPTH 1000. 0 05DENS 1024. 4 END05ACCG 9. 807
AQWA-NAUT
06 FDR1 06FI LE 06CSTR 1 END06CPDB
07 WFS1 07ZCGE END07FI DD 08 NONE 09 DRM1 09FI DD END09 10 HLD1 10WI FX 1 . . . . END10CURZ 6 11 NONE 12 NONE 13 WAVE 13WAMP 13WVDN END13PERD
Example 1
(cont.)
Copy AQWA-LINE database
AL**** **. HYD
- 2. 0000 9. 986E08
1. 0373E5
1. 5702E6
1. 0E07
4. 0E09
2. 0E10
5
1. 460E3
1. 692E3
1. 685E3
1. 175E3
3. 745E2
9
0. 808E7
0. 220E8
0. 191E8
0. 0
12. 0 135. 0 12. 00
5. 000E09
Regular wave parameters
AQWA-NAUT 14 MOOR 14COMP 20 14ECAT 14ECAT 14ECAT 14NLI N 1 14NLI N 1 14NLI N 1 END14NLI N 1 15 STRT END15POS1 16 TI NT END16TI ME 17 NONE 18 NONE 19 NONE 20 NONE
30
3201 3201 3201 3201
3
0 0 0 0
280. 150. 00 120. 00 170. 00
(cont.) 300. 0. 00 0. 00 0. 00
6. 0000E8 9. 0000E8 6. 0000E8
7. 500E6 7. 500E6 7. 500E6
500. 0 500. 0 700. 0
5001 5002 5003 5004
213. 000 2000
Example 1
1. 0
- 213. 000
- 2. 00
0. 000
0. 000
144. 0
AQWA-NAUT
Example 2
Job card for NAUT run J OB TANK NAUT I RRE TI TLE OPTI ONS REST PBI S CONV RDEP END RESTART 4 5 ABTANK6 09 DRM1 . . . 13 SPEC 13SPDN 13CURR 13WI ND END13PSMZ . . . 16 TI NT END16TI ME 17 NONE 18 PROP END18PREV 5 19 NONE 20 NONE
315. 0 1. 00 25. 00 0. 3000
2000
SI NGLE TANKER WI TH CABLE DYNAMI C
Irregular wave analysis
CONV mandator y 315. 0 315. 0 2. 0000
0. 5
4. 000
8. 000
Useful options in AQWA NAUT
IRRE
IRREgular wave analysis (CONV mandatory)
CONV Use CONVolution LSTF
Linear STiFness. Uses hydrostatic stiffness from LINE without modification.
RDEP
ReaD Equilibrium Position
Multiple structures (1) without hydrodynamic interaction
Wave, wind, current directions
Multiple Structures
(1)
without hydrodynamic interaction
Node definition: ●
One set of nodes can be used. ELM1 and ELM2 use different node numbers to define the elements. This can be inconvenient. E.g. if two models are created from .lin files in the AGS, both will have node number starting at 101.
●
STRC card in Deck 1 allows the same node numbers to be used for different models.
AQWA-LINE
(AL2TANK1)
JOB MESH LINE TITLE TWO TANKER WITHOUT HYDRODYNAMIC INTERACTION OPTIONS REST LDOP NQTF GOON END RESTART 1 3 01 COOR 01STRC 1 01 1 0.000 0.000 5.000 . . . . .
Node definition for structure 1
01 999 110.552 0.000 15.000 * ATTACHMENT POINTS ON STRUCURE 1 FOR MOORING LINE BETWEEN ST#1-2 015501 0.000 0.000 15.000 015502 230.000 0.000 27.000 01STRC 2 01 1 0.000 0.000 5.000 . . . . . . . . Node definition 01 999 110.552 0.000 15.000 * ATTACHMENT POINT ON STRUCURE 2 FOR MOORING LINE BETWEEN ST#1-2 015501 0.000 0.000 15.000 015502 END01
230.000
0.000
27.000
for structure 2
AQWA-LINE 02 ELM1 02SYMX 02QPPL DIFF . . . . . END02PMAS 02 ELM2 02SYMX 02QPPL DIFF . . . . . . END02PMAS 02 FINI 03 MATE 03 END03 04 GEOM 04PMAS END04PMAS
(cont.)
Element definit ion of ST#1 1 (1)(
101)(
1)(
6)(
102)
Material no. of ST#1 0 (1)(
999)(
1)(
1)
1 (1)(
101)(
1)(
6)(
0 (1)(
1 1.23009E8 2 1.23009E8 1 2
957.0E7 957.0E7
999)(
2)(
0.000000 0.000000 0.0 0.0
102)
Geometr y no. of ST#1
2)
0.000000 0.000000 0.0 19050.0E7 0.0 19050.0E7
Material and geometry definitio n of ST#1 0.0 19050.0E7 0.0 19050.0E7
AQWA-LINE (cont.)
05 GLOB 05DPTH 500.0 05DENS 1024.4 END05ACCG 9.807 06 FDR1 06FILE ALTANK4.HYD 06CSTR 1 END06CPDB 06 FDR2 06FILE ALTANK4.HYD 06CSTR 1 END06CPDB 07 WFS1 07ZCGE 0.0000 END07FIDD 07 WFS2 07ZCGE 0.0000 END07FIDD 08 NONE
1.000E9
1.000E9
AQWA-LIBRIUM : Multiple structures (AB2TANK1)
JOB TANK LIBR TITLE TWO-TANKER WITHOUT HYDRO. INTER. OPTIONS REST PBIS END RESTART 4 5 AL2TANK1 09 DRM1 09FIDA 1.0373E6 1.5702E7 1.0E12 1.0E15 09FIDD 1.80E5 1.80E6 1.0E10 1.0E13 END09 09 FINI 10 HLD1 10WIFX 1 . . . . . END10CURZ 6 10 HLD2 10WIFX 1 . . . . . END10CURZ 6
1.0E15 2.2564E11 1.0E13 1.00E10
FINI if no data for STR 2 5
1.460E3
1.692E3
1.685E3
1.175E3
3.745E2
10
0.808E7
0.220E8
0.191E8
0.103E8
0.00000
5
1.460E3
1.692E3
1.685E3
1.175E3
3.745E2
10
0.808E7
0.220E8
0.191E8
0.103E8
0.00000
AQWA-LIBRIUM (cont.) . . . . 14 MOOR 14COMP 20 30 14ECAT 14ECAH 14ECAT 14ECAT 14NLIN 1 5001 14NLIN 1 5002 14NLIN 1 5003 14NLIN 1 5004 14LINE 1 5501 END14LINE 1 5502 15 STRT 15POS1 15POS2 END 16 LMTS 16MERR 16MMVE END16MXNI 1200 17 NONE 18 NONE 19 NONE 20 NONE
3
0 0 0 0 2 2
490. 150.00 1.00 120.00 170.00
510. 0.010 0.010 0.010
6001 6002 6003 6004 5501 5502
1.50E7 1.50E7
100.0 100.0
100.00 -215.00
0.000 -000.00
0.000 0.000
0.05 2.00
0.05 0.5
0.05 2.00
6.0000E8 1.33 9.0000E8 6.0000E8
7.500E6 0.10 7.500E6 7.500E6
400.0 500.0 700.0
Mooring line between str#1-2
Initial position of COGs 0.000 0.000
0.1 1.0
0.000 0.000
0.1 1.0
0.000 0.00
0.2 2.0
Iterative control
Use of FINI card Lots Lot s of occasions to use FI FINI card card ●
Deck De ck 2 (compulsory)
●
Multi ultiple ple struct ures, not all of t hem defined defined in deck 6,7,8,9,10
End of deck
●
Multiple confi guration gurations s of mo oring lines (B/F (B/F), insert FINI to sepa separate rate two definitions of moo ring systems
●
Multi ple user defined Multiple defin ed wave spect spectrum rum s (B/F), (B/F), insert FINI to separate ea each ch set s et of UDEF cards
Between Betwe en two sectio ns
AQWA-NAUT: AQWA-NA UT: Multiple str structures uctures (AN2TANK1) Read equilibrium position JOB TANK NAUT IRRE TITLE TWO-TANKER WITHOUT HYDRO. INTER. OPTIONS REST CONV RDEP END RESTART 4 5 AB2TANK1 09 DRM1 09FIDA 1.0373E6 1.5702E7 1.0E12 09FIDD 1.80E5 1.80E6 1.0E10 END09 09 DRM2 09FIDA 1.0373E6 1.5702E7 1.0E12 09FIDD 1.80E5 1.80E6 1.0E10 END09 10 HLD1 10WIFX 1 5 1.460E3 1.692E3 1.685E3 . . . . END10CURZ 6 10 0.808E7 0.220E8 0.191E8 10 HLD2 10WIFX 1 5 1.460E3 1.692E3 1.685E3 . . . . END10CURZ 6 10 0.808E7 0.220E8 0.191E8
1.0E15 1.0E13
1.0E15 2.2564E11 1.0E13 1.00E10
1.0E15 1.0E13
1.0E15 2.2564E11 1.0E13 1.00E10
1.175E3
3.745E2
0.103E8
0.00000
1.175E3
3.745E2
0.103E8
0.00000
AQWA-NAUT
(cont.)
. . . . 13 SPEC 13SPDN 13CURR 13WIND END13PSMZ 14 MOOR . . . . . END14LINE 1 5501 * 15 STRT * 15POS1 * END15POS2 15 NONE 16 TINT END16TIME 2000 . . . . . 20
315.0 1.00 25.00 0.3000
315.0 315.0 2.0000
4.000
2 5501
1.50E7
100.0
100.00 -215.00
0.000 -000.00
0.000 0.000
8.000
0.000 0.000
0.000 0.000
0.000 0.00
0.5
Due to RDEP
NONE
Time step control
Multiple structures (2) with hydrodynamic interaction ■ calculate hydrodynamic coefficients which take
full account of hydrodynamic interaction. ■ up to 20 interacting structures can be included.
AQWA-LINE
(AL2TANK2)
JOB MESH LINE TITLE TWO TANKER WITH HYDRODYNAMIC INTERACTION OPTIONS REST LDOP NQTF GOON END RESTART 1 3 01 COOR 01STRC 1 *234567890123456789012345678901234567890123456789012345678901234567890 01 1 0.000 0.000 5.000 . . . . . 01 999 110.552 0.000 15.000 * ATTACHMENT POINT ON STRUCURE 1 FOR MOORING LINE BETWEEN ST#1-2 015501 0.000 0.000 15.000 015502 230.000 0.000 27.000 01STRC 2 01 1 0.000 0.000 5.000 . . . . 01 999 110.552 0.000 15.000 * ATTACHMENT POINT ON STRUCURE 1 FOR MOORING LINE BETWEEN ST#1-2 015501 0.000 0.000 15.000 015502 230.000 0.000 27.000 END01
Deck 0-1 similar to AL2TANK1.DAT
AQWA-LINE (cont.) 02 ELM1 02SYMX 02QPPL DI FF . . . . . 02TPPL 02RMXS 02PMAS 02PMAS 02PMAS 02PMAS 02PMAS 02PMAS 02PMAS
1 ( 1) (
1) (
6) (
102)
45 ( 1) ( 4606) ( 4506) ( 4507) 0 0 0 0 0 0 0
END02MSTR
02
101) (
( 1) ( ( 1) ( ( 1) ( ( 1) ( ( 1) ( ( 1) ( ( 1) (
999) ( 5001) ( 5002) ( 5003) ( 5004) ( 5501) ( 5502) (
2) ( 3) ( 3) ( 3) ( 3) ( 3) ( 3) (
Remove geometric symmetry
2) 3) 3) 3) 3) 3) 3)
Elements for attachment points. Needed when MSTR card used.
(999) (212.3182, -221.0850,5.5864)
Move structure
ELM2
02HYDI
1
. . . . . . . . END02MSTR
02 03 03 03
Hydrodynamic interaction
(999) (247.5926,-314.7867, 5.6123)
FI NI MATE
END03
04 GEOM 04PMAS 04PMAS END04PMAS
1 1. 23009E8 2 1. 23009E8
0. 000000 0. 000000
0. 000000 0. 000000
3 1.00000E0
0.000000
0.000000
1 2
957. 0E7 957. 0E7
0. 0 0. 0
0. 0 19050. 0E7 0. 0 19050. 0E7
3
1.0E0
0.0
0.0
0.0
Fictitious material and geometric properties for attachment points 0. 0 0. 0
19050. 0E7 19050. 0E7
0.0
0.0
AQWA-LINE (cont.) . . . . 06 FDR1 06FREQ 1 06FREQ 7 06DI RN 1 06DI RN 6 06DI RN 11 END06DI RN 16 06 FDR2 06FREQ 1 06FREQ 7 06DI RN 1 06DI RN 6 06DI RN 11 END06DI RN 16 07 WFS1 07ZCGE END07FI DD 07 WFS2 07ZCGE END07FI DD 08 NONE
6 11 5 10 15 19
0. 10000 0. 70000 - 180. 00 - 80. 00 20. 00 120. 00
0. 20000 0. 80000 - 160. 00 - 60. 00 40. 00 140. 00
0. 30000 0. 90000 - 140. 00 - 40. 00 60. 00 160. 00
0. 40000 1. 00000 - 120. 0 - 20. 0 80. 0 180. 0
0. 50000 1. 10000 - 100. 00 0. 00 100. 00
0. 60000
6 11 5 10 15 19
0. 10000 0. 70000 - 180. 00 - 80. 00 20. 00 120. 00
0. 20000 0. 80000 - 160. 00 - 60. 00 40. 00 140. 00
0. 30000 0. 90000 - 140. 00 - 40. 00 60. 00 160. 00
0. 40000 1. 00000 - 120. 0 - 20. 0 80. 0 180. 0
0. 50000 1. 10000 - 100. 00 0. 00 100. 00
0. 60000
No symmetry, -180 to +180
0. 0000 1. 000E9 0. 0000 1. 000E9
Note: wave frequencies and directions MUST be same for hydro. interacting structures
Multiple structures (2) with hydrodynamic interaction The PFIX method (Deck 2)
• Combine a floating and a fixed model into ONE structure • Put fixed part into a specified group • Use the PFIX card in Deck 2 to “ground” the fixed model
Symmetry
SYMX means that AQWA can assume that the analysis is symmetric ABOUT THE FRA X-AXIS. This allows timesaving shortcuts to be used in the solution. RMXS removes symmetry, creating a full model (even though the model may still be a symmetric structure). It only applies to T/QPPL elements, not to other elements or nodes. MSTR moves the structure to a new definition position. It only applies to elements and associated nodes, not to all nodes listed under the STRC card. It actually moves the nodes and elements in the FRA. It is not the same as the POS card in Deck 15. SYMY and RMYS have the same effect relative to the Y-axis
LIDS ●
ILID to remove irregular frequencies inside structures
●
can be automatically generated VLID to reduce standing waves between structures has to be defined by user
LIDS (cont) 02 ELM1 02I LI D AUTO 02VLI D 02SYMX 02QPPL DI FF . . . . . 02PMAS 02MSTR 02QPPL DI FF 02QPPL DI FF . . . . . END 02 ELM2
( LI D_SI ZE=2. 0, START_NODE=5000) 777 ( DAMP=0. 01, GAP=8. 0) 1 ( 1) (
101) (
1) (
6) (
102)
0 ( 1) ( 999) ( 2) ( 2) ( 999) ( 212. 3182, - 221. 0850, 5. 5864) 777 ( 1) ( 4606) ( 4506) ( 4507) ( 4508) 777 ( 1) ( 4607) ( 4508) ( 4509) ( 4510)
02HYDI
1
. . . . . . . . END02MSTR
02
(999) (247.5926,-314.7867, 5.6123)
FI NI
ILID elements can be generated automatically VLID elements must be defined in .dat file
Constraints in AQWA
(deck 12)
1) Omission of Motion in User Specified Degrees of Freedom (D.O.F) DACF Ns Ndof (Ns: structure number; Ndof : D.O.F. number),
(PRAF may need)
2) Mechanical Articulations between Structures Relative translational motion is not allowed, but relative rotational motion is possible. DCON
Nt
Ns1
Nd1 (Nd3)
Ns2
Nd2 (Nd4) Nd4
Nt: number of D.O.F. being locked by this constraint. Nt=0: Ball and Socket, rotation in 3 D.O.F. Nt=1: Universal joint, rotation in 2 D.O.F. Nt=2: Hinge, rotation in 1 D.O.F. Nd3 Nt=3: Rigid connection, no rotation.
Ns1
Ns2
Nd1, Nd2
Constraints in AQWA (example)
1
Stinger model constraints
Constraints in AQWA (example) JOB MESH LIBR TITLE NORWAY SHIP + FLEXIBLE STINGER OPTIONS REST GOON NPPP END RESTART 1 5 01 COOR STRC 1 1 115.000 0.000 0.000 .... * Nodes for third part of stringer STRC 3 016001 0.000 -2.000 .... END016025 02 ELM1 02SYMX 02QPPL DIFF .... END02TUBE .... 02 ELM3 02TUBE .... END02TUBE 02 FINI
12.000
0.000
0.000
4.000
(43)( 1,7)( 2,7)( 9,7)( 8,7)
(1)( 6020)( 6017)(2)(2)
(1)( 6001)( 6002)(2)(2)
(1)( 6020)( 6017)(2)(2)
Constraints in AQWA (cont.)
03 MATE 03 END03 04 GEOM 04PMAS 04TUBE END04TUBE ....
1 2
1.242E8 7850.0
1 2 3
957.0E7 0.500 1.000
12 CONS 12DCON 2 1 6023 6020 END12DCON 2 2 6023 6020 13 NONE 14 MOOR 14LINE 1 5201 2 6025 END14LINE 2 6024 3 6022 ....
0.0 0.050 0.050
0.0 19050.0E7
2 6021 6004 3 6021 6004
5.0E05 5.0E05
20NONE
Constraint type: 2 - hinged
25.0 0.0
0.0 19050.0E7
Define a constraint from St#1 to St#2
Definition of Tethers Tethers in a TLP Model
Two types: Towed and Installed; Bending & lateral motion only; Material defined in Deck 3 as flexible tube with Young’s modulus; Small inline deformation defined by TSPV/TSPA cards.
Definition of Tethers (cont.)
JOB TETH
NAUT
TITLE
TETHERS
OPTIONS REST END RESTART
4
09
5
NONE
Material no.; see I.8.1.3
. . . . . . 13
Vessel, Node#1
WAVE
13PERD
9.0
13WVDN
0.0
END13WAMP
8.0
14
Geometry no. Node#303
MOOR
14TELM
300
301
2
2
14TELM
301
302
2
2
14TELM
302
303
2
2
14TSPV
0.0
5730.0
5730.0
14TSPA
0.0
5730.0
5730.0
14TETH
1
1
0
401
END14TETH
1
2
0
402
15
STRT
. . . . . .
Define tether elements;
Node#300 Define tether lines
Start from tail/anchor; Min.2; max. 14/24
Sea bed, Node#401
Definition of Tethers (cont.) I n whi ch: def i nes a t et her el ement whi ch consi st s of t wo nodes ( number s 300 and 301) , and t he el ement has a mat er i al pr oper t y number 2 and geomet r y pr oper t y number 2. The mat er i al pr oper t i es ar e t he mat er i al densi t y and t he Young’ s modul us of t he mat er i al , and t he geomet r y pr oper t i es ar e t he same as t hose f or TUBE el ement s, i . e. di amet er , wal l t hi ckness, Cd and Ca val ues. Not e t hat t et her el ement s ar e def i ned i n deck 14, not i n deck 2. TELM
– TSPV
300
301
2
2
-
speci f i es t he r ot at i onal st i f f ness at t et her at t achment posi t i on t o t he vessel ( moment / r adi ans) TSPA – s pec i f i es t he r ot at i onal s t i f f nes s at t et her anchor pos i t i on ( moment / r adi ans) ber s and node number s t o whi ch t hi s TETH - speci f i es t he st r uct ur e num t et her i s connect ed. Each TETH car d def i nes a compl et e t et her whose el ement s ar e def i ned by t he TELM car ds.
Running AQWA 1.
Drag/drop data file on to desktop icon
2.
From command prompt: Type ‘aqwa57d filename.dat’
3.
Using an AQWA command file (see App.2)
4.
DOS batch file
Linearity
HydroStatics
Diff / Radiation
FroudeKrylov
Drift Force
Mooring Force
Drag
LINE
LIN
LIN
LIN
2nd order
-
-
LIBRIUM eqm
NON
LIN
LIN
2nd order
NON
Linearised
LIBRIUM stability
LIN
LIN
LIN
2nd order
LIN
Linearised
FER
LIN
LIN
LIN
2nd order
LIN
Linearised
DRIFT
LIN
LIN
LIN
2nd order
NON
NON
NAUT
NON
LIN
NON
-
NON
NON
AQL – AQWA Interface for Excel ●
Direct access to AQWA database using Excel function calls
●
Recovery RAOs
●
Recovery time history results
• Installation: (1) AQL32.DLL in c:\Program Files\Microsoft Office\ Office11 (2) AQL32.XLA in c:\Program Files\Microsoft Office\ Office11\Library (3) Set up locati on in Excel\Tools\Add-ins\Browse & Excel\Edit\Links
AQL function&value
Introduction of AQWA-Workbench ANSYS Workbench Envi ronment is a working platform that offers
an efficient and intuitive user interface, ● superior CAD integration ● automatic meshing ● access to model parameters and to the functionality available within the ANSYS Mechanical products. ●
High quality automatic meshing tool
Change/enhance design by Design-modeller
Geometry/design parameters retrieved from CAD
Advanced Post-processing
AQWA-WB
Workbench implementation for the AQWA suite ● At R12 this covers – Import of geometry from DesignModeler – Point mass and disc element definition – Interactive data modification and editing – Native meshing – Diffraction/Radiation analysis – Graph plotting – Wave surface and pressure contour plots ●
The AQWA Simulation Process
CAD
DesignModeler
Hydrodynamic Diffraction
AQWA-WB Meshing – Analysing – Post processing
Project arrangement in AQWA-WB ● Tree view ● Define parameters via sub-windows
Model visualization and hydrostatic results
Messages and graphical plotting window
AQWAWB What it does NOT provide (R12, hydrodynamic diffraction)
- Development of mooring and environmental data Only main functions of AQWA-Diffraction are covered What it will pr ovide (R13, hydrodynamic time response)
- Mooring and environmental data - Time domain analysis Detailed AQWA-WB training material see
WB-HD_AQWA Training Course_Jun2010.pptx
Trouble shooting (1) If you have problems with an AQWA analysis:1. Check the .mes AND .lis files for messages. 2. Run Stages 1 and 2 only if necessary. 3. Check the hydrostatic information output at the end of Stage 2: ● are mass and buoyancy equal? ● is LCG above LCB? ● are resultant forces all zero (or very small)? ● is VCG in the correct position? 4. View model in AGS ● ●
are there any gaps? are inside and outside surfaces defined correctly?
Trouble shooting (2) If the model seems to be correct: 1.
Check the starting position defined in Deck 15.
2.
Check the individual forces in the .lis file. Do they all have the expected magnitude and sign?
3.
If a time domain analysis diverges, run to the timestep before it fails. This may show the development of the problem.
4.
If using convolution in DRIFT or NAUT check added mass, damping and C.I.F. using convolution pages in AGS.
5.
Run a decay test to check damping. Apply an initial displacement, with no waves. The response can be used to calculate % critical damping in the AGS [Cc=sqrt(MK)]
6.
Fix the model with an articulation. This gives output of the applied forces on the vessel which can provide a clue to the problem.
