Numerical simulation of submarine motions in three degrees of freedom in irregular waves for drag force estimation

Investigating the effects of free surface on submarine motion near the free surface of water is important. In the present study, the simulation of a submarine near the free surface of water in irregular waves was carried out. To simulate submarine motion, Suboff geometry with appendages was used. For simulating, URANS method with overset grid approach, k-ε realizable turbulence model and vof in Star CCM+ software were used. The validation , uncertainty and accuracy of the results were implemented. Since the freedom of submarine motions may have significant effect on the results of the drag force, the simulations were performed with considering the three motions of heave, pitch, and roll. Differrent simulations were carried out with different wave heights and wave directions. The results showed that increasing the pitch amplitude due to increasing the wave height ,causes to increase the drag force. For significant wave height of 0.43 meters, the maximum drag force in head and beam sea were 444N and 322N respectively.