b'Marine | Engineer InnovationThe plume structure can be visualizedplume, particularly near small spacesAs part of their as an isosurface of the mass fraction aton the ship sides. Using Simcenter a specified level. Concentrations of theSTAR-CCM+ simulation of the plume different exhaust gases can bebehavior on the full-scale shipdrive to create monitored across the complete model,geometry is possible, preserving all of and any areas that showits detail. The CFD analysis gives athe most concentrations higher than themuch greater understanding of the full required level can be easily found. character of the flow, both around the ship and the plume. STX France nowenergy-When looking at an initial design, STXroutinely uses Simcenter STAR-CCM+ France focuses first on the mostto perform the plume dispersionefficient and extreme configurations of wind speedstudies in CFD instead of wind and direction. As the design is refined,tunnel tests. a wider range of more detailedBecause smell comfort is such acomfortable, configurations is analyzed, covering wind from all directions and at threesubjective measure, it is not easy tobest-in-class different strengths. The exhaust speedvalidate the CFD studies. STX France can also be altered, depending on thehas, however, been able to compare its ship operation profile. There are morepredictions created using Simcenterships, STX than 25 main outlets on theSTAR-CCM+ with readings on a superstructure of the ship. To reducecompleted ship, and the correlationFrance is the overall number of cases, eachbetween the results gives confidence simulation can have up to eightin using CFD in this way.exhaust outlets, with four or fiveConclusion increasing its different phases being modeled. Even with this, there can be a large numberEnsuring efficient dispersion of of cases for each design. STX Franceexhausts and polluting gases from ause of runs cases in batches on its cluster andcruise ship is critical in providing the has a standard setup for analysisexperience that cruise passengerscomputational allowing for quick comparison ofexpect. A poorly devised funnel design results. can lead to areas with poor smell comfort, which will be underused byfluid dynamics A standard shipbuilding contract takescustomers. As space is at a premium, up to three years, from signing toship owners do not want to riskas part of the delivery of the built ship. The plumepassenger discomfort or create vacant analyses are carried out as part of thereal estate. By running CFD initial detailed design phase in the firstsimulations in Simcenter STAR-CCM+,design six months of the contract. During thisSTX France is able to analyze the phase, STX France works closely withcomplete ship geometry at full scale,process.the ship owner, sharing the results ofand therefore predict the plume these CFD simulations and givingdispersion and exhaust concentration feedback on the suggested design.at any point on the structure. They use There can be multiple design iterationsthis information to provide feedback to before a final design is agreed upon;ship owners and designers during the while aesthetics is important, shipearly design stage. The process is owners will not take the risk of badefficient as multiple exhausts can be plume behavior so this feedback andmodeled in one simulation.iteration are a vital part of the design process. This modeling approach has given a greater understanding of the Confidence in the results characteristics of the plumes and their Prior to using Simcenter STAR-CCM+,potential interaction with the ship STX France performed wind tunnelsuperstructure than was possible tests to look at plume dispersion.before, and has now replaced wind While it was easy to make quick designtunnel testing for exhaust dispersal alterations in the wind tunnel andprediction in the design phase. Using repeat results, the scaled model sizeSimcenter STAR-CCM+ is helping STX limited the level of detail that could beFrance to develop and build some of captured. This limitation gave somethe most successful cruise ships sailing uncertainty on the behavior of thetoday. n21'