The Calculation of Hydrodynamic Coefficients for Underwater Vehicles

Maritime Platforms Division within DSTO is currently studying the emerging science and technology of autonomous underwater vehicles for defence applications. As part of an examination of the requirements for the hydrodynamics and manoeuvrabilty of these vehicles MPD has been tasked with the development of models to determine the hydrodynamic coefficients of simple and complex submerged bodies as a function of their shape. These coefficients are specific to the vehicle and provide the description of the hydrodynamic forces and moments acting on the vehicle in its underwater environment. This report provides a detailed discussion and evaluation of three of the existing methods which have been documented in the literature for the calculation of these coefficients. Sample calculations using some of these techniques are presented, and the accuracy and applicability of these calculational methods to the underwater vehicles of interest to the DSTO are described. It is concluded that none of the methods surveyed has the necessary generality to encompass all the shapes of interest to DSTO work, and alternative computational techniques are recommended which should allow the hydrodynamic coefficients of more complex underwater vehicles to be determined.