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© 2011 ANSYS, Inc. February 28, 2012 1

AQWA Update

Chris Burden

ANSYS UK Horsham


Overview

• For those that don’t know, what is AQWA?

• Recent release updates

• 14.0 Update


• AQWA is a modularised , fully integrated hydrodynamic analysis suite based around 3D diffraction and radiation methods.

• AQWA has now been implemented as an ANSYS Workbench application.

• Extensively used in the offshore oil and gas and renewables sector.

What is AQWA?


Shielding

FPSO & TLP Concept Self-installing platform – Arup Energy

Offloading operation – SBM

Typical Applications

Mooring systems

Multi-Body Lift Operation


Jacket launch

Lifting operation – AMOG Truss spar – Technip

Floatover

Typical Applications

Stinger

Truss spar – Technip


Other Applications

Ocean Treader – Courtesy Green Ocean Energy Ltd

Wave Treader – Courtesy

Green Ocean Energy Ltd


Tanker Under-Keel Clearance

Investigation of clearance between tanker keel and channel

Tanker is moving along the channel


Aquaculture Applications – Offshore Fish Farms

Investigate integrity of floating offshore fish farm systems

Novel solution includes modeling both internal and external fluids


Float Design

Marine applications can include multi-body simulations of piled floats


• Diffraction and Radiation including Morison

elements

• Frequency domain analysis

• Stability including mooring lines

• Time domain with irregular waves

• Time domain with non-linear survival waves

• Coupled cable dynamics

• Multiple hydrodynamic interaction and articulations

(up to 50 structures)

• Transfer of motions and pressures to ANSYS FE

models

AQWA Capability


Diffracting or non-diffracting panels

Morison elements

– TUBE

– STUB

– DISC

Point masses

Mixed models

Modelling in AQWA


Moorings

– Linear springs

– Elastic catenaries

– Intermediate buoys

– Tethers

– Pulleys

Fenders

Articulations

Stiffness matrix

Modelling in AQWA


Waves

• Regular / irregular

• Time history

Current

• Uniform

• Profile

Wind

• Uniform

• Spectra

• Time history

Wave Spectra

– Pierson-Moskowitz

– JONSWAP

– Gaussian

– User-defined

– Cross-swell

• Multiple simultaneous spectra

• Interaction between spectra from different directions

Modelling in AQWA


Historical Perspective of AQWA

LIBRIUM

WAVE

ANSYS ASAS

(FE model)

ANSYS

Mechanical AGS

FER NAUT DRIFT

LINE

EXCEL


Historical Perspective of AQWA

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 !!!

JOB MESH LINE

TITLE MESH FROM LINES PLANS/SCALING

OPTIONS REST END

RESTART 1 2

4col 4col5cols5cols 10 cols 10 cols 10 cols

01 COOR

01 1 45.000 -45.000 0.000

END01 999 0.000 0.000 -10.620

Column 21

02 ELM1

02QPPL DIFF 0(1)( 1)( 2)( 12)( 11)

06FREQ 1 6 0.10472 0.15708 0.25133 0.41888 0.52360


AQWA Hydrodynamic Simulation Procedure


AQWA Workbench Application

• At ANSYS Revision 12 AQWA was developed using Workbench technology, permitting importation of DesignModeler geometries, and utilizing ANSYS meshing technology as an integrated tool, but was not available from the WB Project Page

• Was distributed with the standard AQWA suite as a new application, AQWAWB

DesignModeler CAD AQWAWB


• Hydrodynamic Diffraction and Hydrodynamic Time Response represent an ANSYS Workbench implementation of the ANSYS AQWA hydrodynamic software

• Provides a common look and feel across the ANSYS product suite

• Provides for future interoperability with other physical models in the ANSYS product suite, e.g. ANSYS Mechanical and ANSYS CFD

AQWA Workbench Application

ANSYS DesignModeler

CAD Import ANSYS

Hydrodynamic Diffraction

ANSYS Hydrodynamic

Time Response

Workbench Project

Par

amet

er

Var

iati

on

• Vessel particulars • Environmental conditions

AN

SYS

Des

ign

Mo

del

er

CAD Import ANSYS

Hydrodynamic Diffraction

ANSYS Hydrodynamic

Time Response

Mechanical

Fluent/CFX

Workbench Project


ANSYS AQWA HD Parameterization


ANSYS AQWAWB Graphing

Provides standard ANSYS Workbench graphing capabilities.

• RAO’s

• 3D plots

• Splitting forces

• Reporting


ANSYS AQWAWB Surface and Pressure Plots


ANSYS AQWAWB Surface and Pressure Plots

Animated Surface Plots


13.0 AQWA in Workbench - Hydrodynamic Time Response System

Hydrodynamic Time Response Analysis System

• Time history analysis of bodies, subject to environmental forces including mooring lines


13.0 AQWA in Workbench - Hydrodynamic Time Response System

Input for the following:

• Cable connections for rigid body motion, wave and mooring line analysis under various ocean environments

• Ocean Environment Definition for Wind, Wave and Current

• Additional Structure Force Time History

• Cable Winching and Failures

• Input of catenary mooring lines

• Graphing of various results

– Displacement, velocity, acceleration


13.0 AQWA Core Developments

Cable Dynamics

• Bending stiffness allows modeling of rigid and flexible risers (previously only rigid risers could be modeled using tethers)

• Non-linear axial stiffness to enable more rigorous modeling of synthetic moorings. Uses polynomial definition of tension v extension.


13.0 AQWA Core Developments

User-defined stiffness matrix connecting separate ships

• This enables mooring system to be included in diffraction/radiation analysis

ISO wind spectrum definition added for dynamic motions analysis


What’s New at 14.0?

Multiple wave spectra in AqwaDrift

• Includes 2nd order interaction terms

• Now allows wave spreading

Linearized drag of Morison elements in diffraction analysis

Improved load mapping to structural model for integrity checks

Wheeler stretching for non-linear wave pressure calculation

Quasi-static non-linear axial stiffness

Continued exposure of core features in Workbench


Hydro-structural design

Geometry modelling

AQWA CFX/Fluent Mechanical

HYDRO-STRUCTURAL DESIGN


Pre-14 ANSYS Load Transfer Requirements

ANSYS DM

Geometry

Hydrodynamic

Mesh

Structural Mesh

AQWAWB Solve

Hyd Database

Control Data

Structural Data

ANSTOASAS

AQWA WAVE

Pressure and

Acceleration

Data

/TITLE, CASE 1001 'H = 2.0 T = 62.8 D = 0.0 P = 0.0'

! COMPONENT ANSY

SFEDELE,ALL,ALL,PRES

FDELE,ALL

LSCLEAR,INER

SFE, 2409, 2,PRES,0, 0.0000E+00, -1.9740E+02, -1.9576E+02, 0.0000E+00

SFE, 2411, 2,PRES,0, 0.0000E+00, 0.0000E+00, -2.0081E+02, -1.9777E+02

SFE, 2412, 2,PRES,0, -1.9558E+02, -1.9503E+02, 0.0000E+00, 0.0000E+00

SFE, 2416, 2,PRES,0, 0.0000E+00, 0.0000E+00, -2.8120E+01, 0.0000E+00

SFE, 41361, 2,PRES,0, -3.9148E+02, -3.8728E+02, -3.8728E+02, -3.9161E+02

SFE, 41362, 2,PRES,0, -3.9092E+02, -3.8734E+02, -3.8728E+02, -3.9148E+02

SFE, 41363, 2,PRES,0, -3.9490E+02, -3.9511E+02, -3.8924E+02, -3.9014E+02

SFE, 41364, 2,PRES,0, -3.9014E+02, -3.8543E+02, -3.8734E+02, -3.9092E+02

ACEL, 1.9891E-07, 4.2397E-07, -1.0044E-02

CGLOC, 0.0000E+00, 0.0000E+00, 2.5400E+01

DCGOMG, 3.0279E-08, -2.4966E-08, 3.1457E-10


14.0 Load Mapping Process

3D Hydrodynamic Panel

Model Global Structural FE Model

(Coarse Mesh for Yielding and Buckling Check)

Geometry Modeler


Load mapping to Mechanical/APDL


Tree Items For Pressure Mapping at 14.0 *DIM,_aqwaAnalysis,STRING,248

*DIM,_runCommand,STRING,248

_aqwaAnalysis(1) =

'C:\ANSYS\LoadMapping_14.0\LoadMapping_files\dp0\AQW\AQW\AQ\Analysis\Analysis'

_runCommand(1) = '"C:\Program Files\ANSYS Inc\v140\aqwa\bin\winx64\AQWA2NEUT"'

*cfopen,run,txt

*vwrite,_runCommand(1),_aqwaAnalysis(1)

/SYS,%s %s

*cfclos

/input,run.txt

_aqwaAnalysis(1) = '%_aqwaAnalysis(1)%_1'

_aqwaDensity = arg1

_aqwaGrav = arg2

_matwat = 2000

_idwat = 2001

_idwav = 2003

! This should be passed as a parameter since units dependent

mp,dens,_matwat,_aqwaDensity

_aqwaDensity=

! This should be passed as a parameter since units dependent

acel,0,0,_aqwaGrav

_aqwaGrav=

! Set up basic wave information

octype,_idwat,basic,ocean,,_idwav

ocdata,1000.0,_matwat

/PREP7

_maxEtypes = ETYIQR(0,14)

*do,_et,1,_maxEtypes

*if,ETYIQR(_et,1),le,0,cycle

*if,ETYIQR(_et,-2),eq,154,then

keyopt,_et,8,_idwat

*endif

*enddo

/SOLU

_waveDir = arg1

_waveHeight = arg2

_wavePeriod = arg3

_wavePhase = arg4

octype,_idwav,WAVE

ocdata,8,_waveDir

octable,_waveHeight,_wavePeriod,_wavePhase

ocread,_aqwaAnalysis(1),ahd

_waveDir =

_waveHeight =

_wavePeriod =

_wavePhase =


Solve


• Enhanced Productivity with Continuing AQWA Integration in Workbench

• Hydrodynamic Time Response system enhancements include – Fenders (similar to contact)

– Articulations (similar to joints)

What Next?


• Integrated (diffraction/radiation, time & frequency domain, regular & irregular waves,)

• Full hydrodynamic interaction

• Ability to add .DLL with external forces (e.g. DP system)

• Up to fifty connected structures

• Integration into ANSYS Workbench

• Modelling flexibility (CAD independent)

• Coupled cable dynamics

• Proven over 30 years of use

• Ability to transfer pressures and motions to Finite element analysis

Summary


Thank You

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