Added Resistance in Short Length Waves on Ship Forms with Blunt Bow

Abstract

It is well known that the calculated added resistance of ship forms with blunt bow in short length waves by the assumption of slender body is considerably small compared with the measured results. In this report, the reasons of difference are discussed. To study the propagation of elementary waves in the flow field around the hull form, which is deformed by the existence of blunt bow ship, numerical calculations are performed by using the ray theory. It is found that some rays of incident waves propagate to the far field, but some rays cannot reach the far field and break by the interaction between the basic flow and the wave field. Added resistance in waves is obtained by integrating the pressure directly over the hull surface and is compared with the measured results. As the results, the reason of difference is fairly clarified and it is shown that the component of wave breaking can be estimated by using the ray theory.