A numerical investigation on Glimm’s method as applied to water sloshing and impacting is carried out. Emphasis is given to the handling and predicting hydraulic jumps. The effects of the spatial and temporal discretizations are examined. Three shallow water problems, 1) dam-breaking problem, 2) water sloshing in a rolling tank, and 3) impact of breaking of a water reservoir, are studied. It is shown numerically that Glimm’s method is stable and converged solutions can be obtained. The characteristics of the hydraulic jumps are well captured by the numerical calculations. The numerical results are in good agreement with either analytical solutions or experimental data.
A fuzzy logic controller is developed for maneuvering control of surface vessels. The fuzzy controller uses a vessel's heading, yaw rate, distance from a reference point, and the velocity of the vessel relative to the reference point as inputs to generate the control outputs. The control outputs include rudder angle, increase in propeller thrust, and lateral bow thrust. The design of the fuzzy controller is simple and does not require a mathematical modeling of the complicated nonlinear system. The core of the fuzzy controller is a set of fuzzy associative memory (FAM) rules that correlate each group of fuzzy input sets to a fuzzy output set. A FAM rule is a logical if-then type statement based on one's sense of realism, experience, and expert knowledge. The effectiveness and robustness of the fuzzy controller are demonstrated through the numerical time-domain simulations of path tracking and dynamic positioning of a Mariner-class hull with use of nonlinear maneuvering equations of motions.
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