JEC COMPOSITES MAGAZINE - Issue #73 - June 2012 - 55

Research & development

design

High-performance simulation for high-performance vessels – Virtual megayachts
Ship design has always been primarily an experience-based skill. While this is still true to some extent today, we increasingly rely on «virtual experience» drawn from computer simulation. The rapid development of fast and unconventional ships since the 1980s would have been impossible without advanced simulation technology. Simulation is especially crucial in megayacht design, where innovative and unusual concepts requested by customers often involve additional risks. - High-performance simulation for high-performance vessels – Virtual megayachts .................p55 - Prospective strategies for composite production .................. p59

Prof. Dr Volker Bertram and Axel Köhlmoos, Germanischer Lloyd

egayachts have grown beyond 200 metres in length; this is just one example of how designers push the limits. Whenever we leave the «comfort zone» of our experience and venture into new designs, simulation ensures that these designs are efficient and not only viable, but also safe. Simulation has become a powerful tool to support better business processes within the megayacht industry by ensuring comfort, increasing design freedom, achieving better designs in less time, and enabling fast and efficient troubleshooting.

Ensuring comfort
Comfort, a key requirement for a megayacht, comprises many aspects. The most important ones are discussed below from an engineer’s perspective. Seakeeping is vital for passenger comfort. For many seakeeping issues, linear analyses (assuming small wave height) provide a fast method to investigate numerous

parameters (wave length, wave direction, ship speed, etc.). Studying extreme motion patterns, particularly those involving slamming, usually requires non-linear computational fluid dynamics (CFD) simulation, which places high demands on computer resources and is limited to relatively short time periods (seconds to minutes). Combining intelligently linear frequency domain methods with non-linear time-domain simulation takes advantage of the strengths of both approaches. These detailed analyses enable designs with considerably improved seakeeping behaviour and passenger comfort. Aerodynamics affect noise and smoke propagation as well as local flow conditions on helicopter decks, sunbathing decks and similar locations. While wind tunnel tests are still widely used, CFD offers the advantage of overcoming scale effects, which can be significant when thermodynamic processes are involved. CFD can be combined with formal optimisation, e.g. to minimise smoke dispersion on decks (see Figure 1). Ventilation system designs are usually based on simple estimates, which often result in over-dimensioned and energyinefficient systems and sometimes poor performance. CFD, on the other hand, delivers detailed insight, leading the way to a smarter layout. Noise and vibration limits are standard elements of building specifications for megayachts. High comfort expectations must

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No73 June 2012 /

jec composites magazine 55

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JEC COMPOSITES MAGAZINE - Issue #73 - June 2012

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #73 - June 2012