This study conducted a comparative analysis between the captive model test results of BB2 submarine model with a scale ratio of 1/15 and the relevant computational fluid dynamics (CFD) results based on an Unsteady Reynolds-averaged Navier-Stokes (URANS) and large eddy simulation (LES) analyses. The URANS results for static drift without propeller condition were validated using the previous numerical results. The static drift, angle of attack, pure yaw, and pure sway test results, as well as the relevant URANS results were compared. In the cases of pure yaw and pure sway, the effects of time step and repeatability were examined. For the static drift condition, an LES analysis was attempted, and the results showed a trend similar to that of the experimental results at a large drift angle.
Maneuvering coefficients are required to simulate the various submarine maneuvering performances at the design stage. Many studies have been conducted on the hydrodynamic characteristics related to the maneuvering motion of submarines based on experimental fluid dynamics (EFD), particularly captive model tests. Captive model test techniques to implement the maneuvering motion of a submarine include the planar motion mechanism (PMM) (Goodman, 1979; Rhee et al., 2000; Kim et al., 2012), rotating arm (Feldman, 1987), and conning motion (Lewandowski, 1991; Rhee et al., 2000; Park et al., 2015).
The recent development and growth of high-performance computing has allowed numerical studies using virtual captive tests and virtual free-running tests based on computational fluid dynamics (CFD) to be performed. Toxopeus (2008) calculated the forces and moments of the DARPA SUBOFF model under straight and oblique conditions using a Reynolds-averaged Navier-Stokes (RANS) solver, and the results were compared with the experimental results. Some differences were observed in the study between the CFD and experimental results for the sway force and yaw moment in the oblique condition. Takahashi and Sahoo (2019) conducted a RANS CFD study for the hydrodynamic performance of the SUBOFF models, and benchmark test data were used for validation. According to their study, there were some discrepancies between the CFD and experimental results for the sway force and yaw moment under drift and turning conditions. Detached eddy simulation (DES) and large eddy simulation (LES) methods are capable of a more precise analysis of small-scale turbulent flow than the RANS method but require considerable computational resources. Suh and Park (2021) performed DES analyses of the SUBOFF model in a straight-ahead condition. They investigated complex vortical flows that developed from the hull boundary layer and appendages.