A velocity decomposition method combining potential and viscous flow for the estimation of submarine's hydrodynamic coefficients

Abstract Estimating hydrodynamic coefficients is important in the design of submarines. To enhance the efficiency of the computational fluid dynamics (CFD) method for evaluating the hydrodynamic performance of submarines, we have developed a velocity decomposition solver for the simulation of a moving body based on the open-source CFD platform OpenFOAM. The total velocity is decomposed into potential flow velocity and non-potential flow velocity. The potential flow velocity is further decomposed into unit components, which can be computed by the proposed method with less interpolation cost. Further, the original potential flow velocity can be recovered by linear summation of these unit velocity components. This avoids solving Laplace equation at each time step. The non-potential flow velocity is solved by using a complementary Navier–Stokes equation in a smaller domain as compared to that used in the conventional CFD method. In addition, a buffer source term is introduced for the transition of non-potential flow velocity to potential flow velocity. Oblique towing test and planar motion mechanism test are numerically simulated using the proposed method, which reveal good consistency between the experimental data and simulation results. This validates the efficiency and reliability of the proposed method in estimating the hydrodynamic coefficients of submarines.