ANSYS AQWA for Hydrodynamic Analysis China Ship Classification Society • RINA ......

© 2010 ANSYS, Inc. All rights reserved. 1 ANSYS, Inc. Proprietary© 2010 ANSYS, Inc. All rights reserved. 1 ANSYS, Inc. Proprietary

ANSYS AQWA

for

Hydrodynamic

Analysis

Richard May

AQWA Development

ANSYS Horsham

© 2010 ANSYS, Inc. All rights reserved. 2 ANSYS, Inc. Proprietary

What is AQWA?

• AQWA is a modularised, fully integrated hydrodynamics analysis suite based around 3-D diffraction/radiation methods.


History of AQWA

• Developed since 1971 (by WS Atkins)

• Owned and developed by Century Dynamics since

2001

• Century Dynamics acquired by ANSYS February 2005

• Now being integrated into the ANSYS Workbench

system


Some Clients

Regulatory Bodies

• ABS (US)

• Lloyds Register (UK)

• Germanischer Lloyd

• China Ship Classification Society

• RINA (Italy)


Some Clients

• US Navy

• SBM Monaco

• SBM Atlantia

• Allseas

• Dockwise

• Huismann Itrec

• VUYK

• Technip

• WorleyParsons

• MSC Gusto

• REpower

• Friede & Goldman

• INTEC

• Arup Energy

• Alion

• Atkins

• AMOG

• D2M

• Moffatt & Nichol

• Noble Denton

• Han Padron

• Krylov Institute

• VersaMarine


ANSYS AQWA - Capabilities

• Diffraction/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 ASAS & ANSYS FE

models


ANSYS AQWA - Applications

• Determination of RAOs

• Wave bending moments

• Splitting Force calculations for Semi-Submersibles

• Design and analysis of mooring systems

• Time history of motions

• Determination of Air Gaps

• Calculation of Shielding Effects of ships and barriers

• Multiple Body Interactions

• Coupled mooring line-structure interaction

• Cable Dynamics with intermediate buoys

• TLP tether analysis


ANSYS AQWA - Examples

Examples of animations created from AQWA analyses


ANSYS AQWA - Examples

Courtesy of GRC


Modelling in AQWA - elements

• Diffracting or non-

diffracting panels

• Morison elements

– TUBE

– STUB

– DISC

• Point masses

• Mixed models


Modelling in AQWA - connections

• Moorings

– Linear springs

– Elastic catenaries

– Intermediate buoys

– Tethers

– Pulleys

• Fenders

• Articulations

• New for v13.0

– Non-linear axial stiffness (CD)

– Cable bending stiffness (CD)

– Stiffness matrix between structures


Modelling in AQWA - environment

• Waves

– Regular / irregular

– Time history

• Spectra

– Pierson-Moskowitz

– JONSWAP

– User-defined

– Cross-swell

• Current

– Uniform

– Profile

• Wind

– Uniform

– Spectra

– Time history


Radiation / Diffraction

• Multiple structures including

hydrodynamic interaction

• Hydrodynamic coefficients

(added mass and damping)

• RAOs

• Drift coefficients (Near / far

field, full QTF matrix)

• SF / BM

• Splitting forces

• Pressure distribution for

transfer to FE

Video\Ship&Box.avi

Video/Ship&Box.avi

Video/Ship&Box.avi

Video/Ship&Box.avi


Load Transfer

• Calculation and transfer of hydrodynamic loads to ASAS and ANSYS

AQWA-LINE

Model

ASAS/ANSYS

Model

Motions & Pressures

AQWA

WAVE

AQWA

Pressure plot

ANSYS

Pressure plot

Images courtesy of Vuyk

Engineering Rotterdam


Equilibrium and Stability

• Computes static

equilibrium position for

multiple environmental

and mooring

configurations

• Preliminary mooring

design

• Calculates static /

dynamic stability

• Video\Librium.avi

Video/Librium.avi

Video/Librium.avi

Video/Librium.avi


Frequency Domain

• Significant motions at low frequency/wave frequency in frequency domain

• Permits rapid analysis using linearisedparameters of mooring systems

• Graphs for response spectra / RAOs & other parameters

• Wave spreading and 2D spectra


Time-history

• Time-history analysis of multiple structures with irregular waves

• Can use full QTF matrix for shallow water conditions

• Import of wave height time history

• Input of forces via user-defined dll

• Output of motions and forces

• Graphical and animation results


Time-history (large waves)

• Non-linear time-history

analysis with large

(survival) waves

• Regular or irregular waves

• Integration of pressure

over wetted surface

• Standard plus sharp

crested wave option


Cable Dynamics

• Additional cost item for

more rigorous

simulation of mooring

line behaviour

• Provides full coupled

vessel/mooring line

analyses

• Included in all modules

except AQWA-LINE


Excel interface

• AQWA specific functions add-in for Excel for

data and results retrieval, processing and

report generation


Graphical Interface

• Automatic mesh generation

from lines plans

• Results presentation

• Graphical manipulation of

results

• Export to spreadsheet

• Function processing e.g.

Nodal RAOs

Fourier transforms

• Model checking


Hydrodynamics in Workbench

• 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


The ANSYS Workbench

simulation process

ANSYS

DesignModelerCAD

ANSYS

Hydrodynamic

Diffraction

ANSYS

Hydrodynamic

Time Response


Surface and Pressure Plots

• Animated Surface Plots



• What it currently provides (Release 13.0):

– Import of geometry from ANSYS

DesignModeler

– Interactive data modification and editing

– Native meshing

– Diffraction/radiation analysis

– Definition of moorings

– Definition of environment

– Graph plotting

– Wave surface and pressure contour plots


PROPOSED FOR v14.0

(no promises!)

• Further integration with Workbench

• Linearisation of Morison drag (LINE and/or FER)

• Multiple simultaneous spectra

• Non-linear axial stiffness for quasi-static

catenaries


Key Differentiators

• 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

• Coupled cable dynamics

• Proven over 30 years of use

• Ability to transfer pressures and motions to Finite

element analysis


ANSYS AQWA

The end

Thank you

ANSYS AQWA for Hydrodynamic Analysis China Ship Classification Society • RINA ......

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