Submarine Seakeeping and Resistance in Irregular Waves

This study presents numerical simulations of submarine motion near the free water surface in the presence of irregular waves, with results compared to calm water conditions. Using the URANS method, the amplitudes of the submarine's heave, pitch, and roll motions were calculated. The hydrodynamic behavior of the submarine was analyzed with STAR-CCM+ in both surface and submerged modes near the free surface. The effects of encounter angles and varying wave characteristics on the amplitude of submarine motions were also investigated. The results show that the largest amplitudes of pitch and heave motions occur in following waves, while the highest amplitude of roll motion is observed in beam waves. Additionally, following waves exhibit the lowest frequency of motion oscillation. In surface mode, due to the increased height of the longitudinal metacenter compared to submerged mode, the amplitude of pitch motions is reduced. However, in surface mode, the stability of the transverse metacenter and the increased influence of wave effects on the free surface lead to greater roll motion amplitudes. The increase in residual resistance in surface mode is greater than the increase in frictional resistance in submerged mode, resulting in higher total resistance in surface mode.