Reduction of Fluid Resistance Acting on Ships by Using Hydrodynamic

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In the present studies, reduction of fluid resistance acting on ships is discussed, which is based on hydrodynamic interactions between the main hull and attached parts like a bulb, a wing, a spike or an outrigger. Investigations on hydrodynamic interactions are carried out experimentally by resistance tests in a towing tank and/or visualization methods in a circulating water channel and numerically by panel methods based on potential theories like Rankine source method or Morino's panel method. As the main themes of the present studies, the following research works are discussed.・Optimization of bow bulb to minimize wave making resistance [Mono-hull]・Reduction of wave making resistance by off centerline bulbs (twin bulbs) [Mono-hull]・Reduction of wave making resistance by bulbs installed on center plane of catamaran [Catamaran]・Wave making characteristics of multi-hull vessels with outriggers or sponsons [Multi-hulls]・Reduction of wave breaking resistance by spike attached in front of bow [Mono-hull with bluff bow]In the cases excluding the last one, the wave making resistance acting on high speed vessels designed at high Froude numbers can be reduced. Especially, in the first case, the bulb shape and the fore body of ships are optimized by means of Rankine source method and the nonlinear programming. In the last one, the wave breaking phenomena can be changed by means of the spike and its availability to reduce the wave breaking resistance is investigated experimentally.