In this study, Star-CCM+ was used as a Reynolds-averaged Naver Stokes (RANS) solver to estimate the seakeeping performance of a submarine, and the results were compared to those of model tests from a published paper ( Hermanski and Kim, 2010). But recently, with the development of computer hardware technology, the value of CFD has been increasing. However, there has been a drawback in that it is difficult for computer hardware to perform large-capacity calculation. Compared to physical experiments, CFD is financially efficient, and the intensity of physical labor is low. The main goal of this study is to improve the numerical accuracy in free surface conditions using CFD. In this study, a Canadian Victoria Class submarine was chosen as a target vessel, and the experimental results have been published in the 2010 11th International Symposium on Practical Design of Ships and Other Floating Structures (PRADS) ( Hermanski and Kim, 2010). In general, a submarine has limited access to public documents due to issues such as military secrets and security maintenance, and it is extremely difficult to obtain related material. For these reasons, research on the seakeeping performance of submarines in free surface conditions is steadily continuing, but only a few papers have been published for security reasons. In addition, submarines have very poor rolling in free surface conditions because they have a rounded shape with very few appendages. Military submarines avoid going out on the water to minimize exposure to enemies, but free surface conditions are unavoidable for port departure and arrival, and it is necessary to study the seakeeping performance in extreme environments ( Burcher and Rydill, 1995). ![]() However, the performance in free surface conditions is also important because submarines face various scenarios. Submarines spend most of their time below the water surface, so the design was optimized for submerged conditions. The hull form of early submarines was similar to those of surface ships, but a rounded hull form was used to reduce water resistance and increase speed for tactical planning ( Krishna and Krishnankutty, 2016). Over the last 100 years, since the development of the diesel-powered submarine by the French Navy in 1863, submarine design has changed remarkably. In conclusion, seakeeping analysis based on CFD can be a good solution for estimating the seakeeping performance of submarines in free surface conditions. From the calculation results, it was found that the seakeeping analysis by using CFD gives good results compared with those of potential theory. In addition, the potential theory software Hydrostar developed by Bureau Veritas was also used for seakeeping performance to compare with CFD results. The results were compared to those of model tests. In this study, the seakeeping performance of a Canadian Victoria Class submarine in regular waves was investigated to improve the numerical accuracy in free surface conditions by using computational fluid dynamics (CFD). In the case of a submarine, the accuracy of potential theory is high underwater but is low in free surface conditions because of the nonlinearity near the free surface area. Generally, potential flow theory is used for seakeeping analysis of a surface ship and is known for excellent numerical accuracy. However, the performance in free surface conditions is also important because it is unavoidable for port departure and arrival. ![]() A submarine is optimized to operate below the water surface because it spends most of its time in a submerged condition.
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