ABSTRACT

Having the motion ability also in the vertical plane, the maneuvering problem of underwater vehicles is a challenging subject that requires mathematical consideration of all degrees of freedom to define the trajectory of the vehicle. Studies in the literature, which address this problem, are mainly focused on the deeply submerged condition of the vehicle. These studies are based on the assumption of infinite fluid field that simplifies the problem. Due to the operational requirements such as communication, positioning, meeting the need for breathing and combustion air, and the survey of the seabed etc. it is inevitable for underwater vehicles to approach fluid boundaries. As a result prediction of vehicle's maneuvering performance under the boundary effects is crucial. This requirement causing further increase in the level of complexity and arise new questions. Issues such as out-of-plane forces resulting from interference effects, effects on propulsion parameters and control surfaces and how all these effects will be represented in the maneuvering model are the most important ones. In order to address all these questions alterations in the maneuvering characteristics of the vehicle due to the presence of boundaries must be examined separately and expressed mathematically. The representation of these mathematically expressed effects in the maneuvering model forms the second phase. In this phase; the use of hydrodynamic coefficients which are functions of governing parameters of boundary flows (Froude number, depth, keel-seabed distance, etc.) in the existing maneuvering models is the widely accepted approach in the literature. The option of deriving a new set of motion equations which takes boundary effects into account is currently in the conceptual stage. Extensive use of underwater vehicles in the proximity of fluid boundaries due to the operational requirements has increased the need for academic studies in this field in recent years. This situation motivates the scholars to investigate the different aspects of the above mentioned topic and led to the gathering of a considerable amount of literature. The scope of this study -which constitutes the second part of the main topic of “assessment of the maneuvering characteristics of underwater vehicles”- is to classify the current literature. The topics to be covered are; changes in the horizontal and vertical planes due to the presence of the free surface and the interactions in between, the interactions between the free surface and appendages, free surface and propulsion system and the effects of the seabed. The efforts regarding the representation of all these effects in the maneuvering models are also discussed. Furthermore, additional difficulties brought by the existence of fluid boundaries in to the numerical and experimental analysis of the problem are mentioned. Thus, it is aimed to provide a general assessment of the subject and identify potential research areas that are not addressed in the literature yet.