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Designing ventilation systems for large vessels is highly demanding due to the complexity of the ventilation network, internal obstacles, and numerous branches that must distribute air evenly throughout the entire system. Conventional engineering calculations often cannot fully predict how air will behave in such complex configurations. The team at NCC Croatia collaborated on precisely this type of challenge with Lürssen Design Centre Kvarner, an engineering company specialised in superyacht design.
As part of the collaboration, NCC Croatia provided a range of services tailored to Lürssen’s needs. The first step involved training the company’s engineers in computational fluid dynamics (CFD) and the application of high-performance computing (HPC). The objective of the training was to enable the engineering team to independently use CFD tools in combination with HPC infrastructure, thereby opening up opportunities for faster and more detailed analyses in everyday engineering practice.
In addition to the training, a detailed analysis was conducted on a section of the ventilation system of an active vessel, where measured values significantly deviated from the initial air distribution design. The analysis aimed to identify the causes of these discrepancies: where and why unexpected air distribution occurs, which system components most strongly influence the observed issue, and what possible solutions could be implemented. Furthermore, the study sought to determine whether CFD could effectively model this type of problem and whether, already at the design stage and with the support of HPC resources, results consistent with real operating conditions could be obtained within a reasonable timeframe.
OpenFOAM, a leading open-source software package for CFD simulations, was used for the analysis. The process was carried out on the supercomputing infrastructure available through NCC Croatia. In the preliminary configuration, the primary distribution segment with nine outlet branches was modelled. The initial simplified analysis revealed that the geometry of the system itself caused uneven flow distribution as a direct consequence of duct arrangement and internal obstacles.
These observations were confirmed by on-site measurements on the vessel. In the extended configuration, additional downstream duct segments were introduced to simulate the resistance of the actual distribution network, enabling more realistic simulation of real operating conditions. Complex three-dimensional flow patterns were observed, including secondary circulations, preferential air paths, and zones of flow separation and reattachment around internal obstacles. The established workflow enabled simplified models to be computed in approximately one hour, while more detailed analyses, using HPC resources, required less than twelve hours — making this type of analysis a practical tool in everyday engineering practice.
The collaboration resulted in tangible advancements for Lürssen. The company is now equipped with the knowledge and tools to independently conduct similar analyses, enabling faster development iterations, more efficient testing of design modifications, and shorter development cycles for new systems.
The collaboration was carried out within the activities of the NCC Croatia and the EuroCC 2 project.