Towed underwater vehicle systems are influenced significantly by the presence of the cable, especially in deep water where cable drag and inertial effects are as important as, or even more important than, the drag and mass of the vehicle Itself This paper describes a numerical technique for simulating the dynamics of such a system, based on simplifications of the governing equations which retain the relevant motions and the accuracy of the solution. The ARGO/JASON system at the Woods Hole Oceanographic Institution is used as a case example, verification of some numerical predictions is shown, using full-scale sea data, and other Illustrations are given.
Towed underwater vehicles have a wide range of applications in industry and science. In many cases involving deep water the tether itself may introduce significant dynamic phenomena, due to the large inertial; and drag loads it carries. The dynamics of the tether often are so dominant that the vehicle forces are negligible by comparison. Hence, m order to understand and possibly to improve the dynamics of the underwater vehicle and the system as a whole an accurate model of the cable is necessary. The cable presents unusual difficulties as a dynamical system because t is a mechanism rather than a simple structural member. As a result It accommodates external loads through substantial shape changes. Thus, the cable configuration is itself an unknown and simulation is nonlinear and very complex. In this work we give a technique for solving the axial and lateral dynamics of such a cable/vehicle system. If the dynamic motions are small enough, then a very wide range of scenarios can be effectively simulated Within the linear approximation with no penalty in accuracy. This approach has been advocated for moored systems by Triantafyllou (1982).
