applications Now factor in the extreme and harsh


environments – such as deep waters – in which the oil and gas industry operates. Furlan said: ‘Te real challenge here is not necessarily the soſtware chosen to simulate any phenomenon, but the need to make sure that the final design of technically and economically safe machinery is sufficient to operate in anticipated critical conditions.’


The need for 3D In the past, 1D soſtware tools were used to provide global analysis to design offshore equipment. Read added: ‘Historically, naval architects and offshore engineers have relied on potential flow codes (simple CFD) and physical testing in their design process. While both these methods have advantages, they also leave significant uncertainty in the design.’ For example, potential flow codes do not


account for viscous effects, overturning, or breaking waves, and wave basin tests are scaled by the Froude number rather than the Reynolds number. Read added: ‘Consequently, when designers try to estimate the platform’s tendency for or vortex induced motion VIM – motions caused by vortex shedding from platform legs when a strong current is present – this is a viscous effect, where the behaviour changes as a function of the Reynolds number; they’re oſten highly conservative, resulting in significant additional cost.’ Tis is where multiphysics simulations can


pick up the simulation slack to create models close to the complexities of the real world, as Kan added: ‘Users can couple fluid flow with heat transfer, structural mechanics, electrical signals, and other physical phenomena, allowing them to benefit fully from virtual prototyping by solving systems of equations representing coupled physics effects, as they would occur in nature.’ Te design stage can be quite lengthy,


layer of complexity, as Livio Furlan, chief technical officer for EnginSoſt’s structural and oil and gas competence centre, said: ‘Tis in turn governs the varied design scopes required. So to cope with the different characteristics of any machine, it is essential to know the background detail.’ Ten there are the financial considerations,


as Alex Read, director of business development, oil and gas at CD-adapco said: ‘In this time of low oil prices, cost reduction is front and centre. Simulation is playing a key role to reduce spending on physical testing, deliver projects on time and in budget, and reduce operational expenses by delivering designs that are right the first time.’


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and needs to be optimised. One example of such optimisation is the new MapleSim CAD Toolbox, which allows for easy model preparation through CAD model import. Paul Goossens, VP for engineering solutions at Maplesoſt, said: ‘Customers have designs in a CAD model early on, to see if the components will fit together. We take advantage of the work already done to give a dramatic increase in productivity and reduce design timings from one day to one hour.’ Tis need to improve turnaround times is


a clear business requirement, as Read said: ‘When geometries are complex, engineers spend significant amounts of time fixing CAD and building high quality meshes. When the physics are complicated, for example multiphase flow, the mesh quality requirements are more stringent. STAR-CCM+’s ability to build a


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high quality mesh, combined with a robust multiphase solver, again saves significant time and effort.’


Virtually prototyping platforms Offshore platforms are moving further away from the seashore, which means they must survive in deeper waters and increasingly severe conditions. Tese vessels need to withstand a huge range of indirect and direct effects, such as rogue waves, extreme weather conditions, and even earthquakes over an extended period of time. You cannot physically prototype an entire offshore platform, so virtual prototyping is used. Virtual prototyping evaluates the concepts


and designs against system requirements using numerical simulations, before putting those concepts and designs into production. One key application area is the simulation


of semi-submersible platforms, also known as floating platform storage and offloading (FPSO) vessels. FPSOs were developed as a cost-effective solution to fixed offshore processing facilities and pipelines, as the oil and gas industry moves its operations to deep water locations. FPSOs are floating vessels and can be either


a conversion of an oil tanker, or a vessel built specifically for the application. Tey need to withstand severe conditions to maintain the platform’s structural integrity, production capabilities, living quarters and personnel.


MULTIPHYSICS CAN


CREATE MODELS CLOSE TO THE COMPLEXITIES OF THE REAL WORLD


Arnaud Ribadeau Dumas, solution experience director at Dassault Systèmes, said: ‘Multiphysics simulation, as part of large vessels and platforms engineering, helps to reduce development time and cost, improve quality and power innovation.’ Dumas added: ‘4D simulation enables the user


to simulate all aspects of the construction phase, optimise resources, detect potential problems, and complete the construction ahead of schedule thanks to such virtual modelling techniques.’ Offloading the product for transportation


to another vessel is an integral aspect of FPSO operation, and it is a delicate exercise. Fouad El Khaldi, director of strategy and diversification at the ESI Group, said: ‘Numerous configurations are possible and increasingly larger facilities are now being built, requiring a holistic view and significant rich assessment, containment and optimisation.’ Te relative motions of the two vessels


during offload were simulated, as well as the resulting wave motions, using rigid body models to predict the kinematic motions. Full ➤


DECEMBER 2015/JANUARY 2016 27


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