Simulation of changing and breaking cable and net structures

A method has been developed to numerically simulate the dynamic geometric response of cablenet structures to various influences: fluid drag, gravity, buoyancy, tension/torsion, and arbitrary deployment. The system is constructed from a set of generic elements representing such items as cable links, rings, net twines, sliding nodes, winches, and boats. New elements may be defined and implemented in a straightforward fashion. A mathematical graph organizes the entire problem in a general and flexible way, permitting construction of complicated systems as well as allowing structural redefinition during the simulation. Application of new methods for solving stiff, sparse systems of coupled ordinary differential equations enables efficient simulation of snap-loads and other severe events. The program has been validated by comparison with laboratory measurements and has been applied to the problems of purse-seine tuna fishing and towed acoustic arrays.