The manned diving underwater vehicles (UVs) are emerging as a significant capability enhancer for future generation submarines. During the underwater scheme design period, the calculation of resistance is an important task. In practice, the motions of the vehicles can be decoupled into horizontal and vertical motion. Therefore, estimation of the hydrodynamic coefficients of movement back and forth (horizontal), movement down and up (vertical) is the key to step to predict the motion of the underwater vehicles. Reynolds Averaged Navier-Stokes (RANS) simulations are carried out to numerically simulate the motion cases. This paper provides a detailed evaluation of the influence of seabed and water surface. The Computational results are verified by comparison with the real data that shows this method can be used to estimate the resistance of an underwater vehicle.
