Offshore_ANSYS

Application of Engineering Simulation Solutions in Offshore and Marine

Dr. Steven M. Varnam European Technology Group ANSYS

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Agenda •

Introduction

•

ANSYS Workbench

•

Analysis Capabilities of ANSYS Mechanical Products

•

Analysis of Ocean Environments

•

Examples

•

Roadmap





















Introduction





















Offshore Structures





















Key Market Problems

•

Reliable and Safe Product and Processes:

– – – –

Deep-waters, high pressures Temperature variation Hurricane, Hurricane, waves Dense areas, combustible and hazardous products

– Drilling through complex geology, long distances

– Many production and processing





















Key Market Problems

•

Cost of Failure

– – – –

Human life Environmental concerns Delays and fines Loss of capital, time and equipment













































ANSYS Workbench























ANSYS Workbench •

ANSYS Workbench acts as a common environment for all of our mainstream products – structures, fluids, thermal, electronics .... It enables us to interface interface software software modules directly























ANSYS Workbench























Analysis Capabilities of ANSYS Mechanical

























Analysis Capabilities of ANSYS ANSYS Mechanical

















































Modeling of Ocean Waves

























Modeling of Waves

































































































































































































































































































































Solutions For Complex Ocean Environments





















Need for More Rigorous Solutions •

Limitations of of Potential Flow Solvers

– – – – –

– – •

Importance

– – – •

Not capable for viscous dominated problems Green water behavior, FPSO roll motions, VIV, Hull drag calculation etc Non linear waves Turbulence Key factor in design of offshore structures Green water behaviors on the deck of ship (FPSO) Wave run up on the structures

General Requirements

–

Wave-in-deck loads ( LRFD design criteria) – Hydrodynamic force on the structure – Maximum and Minimum pressures – Duration of pressure peaks





















Computational Fluid Dynamics ( CFD) Examples using Linear/Stokes Wave Theories •

CFD is the simulation of fluid flow and heat and mass transfer by solving conservation equations for mass, momentum, and energy Wave Wave interaction with hull hu ll





















Current loading on Fixed Structures •

•

•

CFD can be used to look at viscous and form drag on a subsea drill fixed to seabed Upstream velocity 1/10 th power law profile Calculation of force components on structure s tructure in three directions

•

Drag force ~ hundreds of kN

•

Lift force ~ tens of kN

© Bauer Renewables Ltd. Ltd.





















Wave Impact Loading on an Offshore Oil Rig (Animation)























Load History During the Wave Impact























Wave-in-deck Analysis of Offshore Oil Rig: Model Details •

Fifth Order Solitary Wave Theory

•

Wave Details:

– Wave Height : 20m – Water Depth: 41m























Mechanical Examples























ANSYS Mechanical Applications •

Offshore Structures

•

Pipelines and Risers

•

Tubulars, connectors























Examples – Linear Static

























Jacket Structural Analysis

























Offshore Structures - Design Solutions

























Code Checks

























Fatigue Assessments

























Fatigue Assessments









































































































































































































































































































Pushover of Oil and Gas Platform •

The ocean loads applied to an offshore structure are calculated using Morison’s equation, which calculates the loads on line elements due to wave and current. This load is calculated for the worst position of the 100 year storm wave in relation to the structure by running one complete wave through the structure and extracting the wave with the largest base shear. This worst case load is then incremented





















Complex Contact Non-linear analyses of umbilicals -

Monito Monitorr applied applied force force on clamp clampss vs plasti plasticc deform deformati ation on during during loading Invest Investiga igatin ting g disto distorti rtions ons in umbil umbilica icall parts parts after after unload unloading ing





















Complex Contact Results: Steel parts – Mises Stress

After loading:





















RAO application •

Example showing RAO application for linear waves and transient spectra.





















Examples – Nonlinear Dynamic























Ship impact























Explicit - Impact























Explicit - Impact























Explicit - Explosion























ANSYS Explicit application examples •

Deck penetration

























Floating Wind Turbine base

























Floating Wind Turbine base

















































Coupling Mechanical with 3rd Party

























Sequential Solution Example









































































































































































































































































































ANSYS Offshore Strategy Mechanical

Aqwa

+

Asas

Global and and Local Local (detailed) FE





















Roadmap - Asas to Mechanical •

•

Aim to retire Asas in favour of Mechanical introduced in Mechanical – Selected capabilities of Asas introduced Key capabilities introduced in Mechanical – Wave theories and loadings – Improved beam modeling – Soil-Pile-Structure Soil-Pile-Structure interaction (Splinter) – Coupling to 3 rd party aeroelastic tools for OWTs – New Design Assessment system in Workbench Workbench Mechanical for

Images Courtesy of REpower Systems AG

customized post-processing post-processing including management of code checking





















Roadmap - Aqwa •

Integration of Aqwa in Workbench with other ANSYS products – Migration ongoing over past 3 releases – Providing links to other relevant modeling and analysis tools parameterization – Providing parameterization

•

Active core developments to Retain Aqwa as a leading software for general purpose hydrodynamics e.g.





















Future Directions •

Mechanical – Replace/repackage current Beamcheck & Fatjack tools – Ongoing offshore specific developments •

Improved beam & shell modeling

•

Replace Splinter in Mechanical

– Integration in “Next Generation” Workbench -based UI •

Aqwa – End-to-end solution in Workbench – Improved performance (HPC)





















Offshore_ANSYS

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