This article discusses the optimum hydrodynamic shape of the submarine stern based on the minimum resistance. Submarines consist of two major categories of hydrodynamic shape: the teardrop shape and the cylindrical middle-body shape. Due to the parallel middle-body shape in most of the naval submarines, those with cylindrical middle-body are studied here. The bare hull has three main parts: bow, cylinder and stern. This article proposes an optimum stern shape by the computational fluid dynamics method via Flow Vision software. In the hydrodynamic design point of view, the major parameters of the stern included the wake field (variation in fluid velocity) and resistance. The focus of this article is on the resistance at fully submerged mode without any regard for free surface effects. First, all the available equations for the stern shape of submarine are presented. Second, a computational fluid dynamics analysis has been performed according to the shape equations. For all the status, the following parameters are assumed to be constant: velocity, dimensions of domain, diameter, bow shape and total length (bow, middle and stern length).

This article describes the evaluation of the wave profile of submarine at surface condition and deck flooding which occurred by the wave making pattern at the bow. Movement of ships and submarines on the free surface of calm water creates the surface wave. Because of the difference in the bow shape and freeboard height, the wave making system in ships and submarines is different. Rounded or elliptical bow shape of submarines generates a high bow wave which causes deck and bow wetness. This is because of the fact that in submarines, this situation arises a small freeboard. In submarines, Deck wetness (because of deck flooding) is a very important subject that has some remarkable consequences, such as increase in resistance and added weigh. The focus of this article is on the added frictional resistance in the deck wetness condition. The bow wave profile, deck wetness and added resistance are studied in several Froude numbers by computational fluid dynamics method. This analysis is performed for a bare hull model at two different drafts by Flow Vision (V.2.3) software based on computational fluid dynamics method and solving the Reynolds-averaged Navier-Stokes equations.