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Assessment of wind heeling lever determined through CFD against the current naval stability standards


 Naval stability standards consider the impact of a number of different external factors, one of which is the effect of heeling caused by wind. With relatively large superstructures the wind heeling moment can be relatively significant but despite its potential impact, at present the calculation to determine the wind heeling moment is relatively simplistic. With increasing fidelity within computational tools, in particular Computational Fluid Dynamics (CFD), it questions whether the current standards are still considered fit for purpose or whether a more time consuming but comprehensive analysis should be used. This paper discusses work conducted by QinetiQ on behalf of the UK MoD, to explore this area. The work firstly benchmarks wind heeling moment derived by different CFD methods against existing model wind tunnel test results for a heeled patrol boat. The benchmarking compares the level of accuracy of the numerical tools and explores the impact of changing different parameters within the analysis. Following the benchmarking at model scale, CFD is used to calculate the wind heeling force on two ships at full scale.  The two selected ships represent very different types of hullform and ship particulars.  The results from the CFD analysis are then compared to the results determined using current naval standard wind heeling criteria. This paper discusses the different CFD methodology applied, the results from the benchmarking, the comparison between the CFD results and those determined by applying the current naval standard criteria and the implications on the applicability of a CFD analysis rather than the current criteria. 
