Abstract/Description

In many applications in seakeeping the added resistance plays an important role. It has been observed that among the existing methods of calculating added resistance, 2-D Strip theory based classical methods are very popular. Although prediction given by these classical methods is reasonable at least from the practical point of view for conventional medium to high speed vessel, but some of their inherent limitations fail to give reasonable results for blunt ship forms which are usually low speed ships. Since there are huge financial activity involved for this particular blunt type ships like bulk carriers/ tankers in the transportation sector of world economy, so their accurate prediction of seakeeping deserves special attention for an economically optimum design. This paper presents the numerical results of added resistance for some fine to blunt type ship using 3-D near field approach. Before solving motion equations, hydrodynamic forces for surface ship advancing in waves at constant speed have been calculated with the help of 3-D source-sink method. The method is then used to calculate total potential & its derivatives in order to achieve the final goal of assessing added resistance in waves using near field approach. The application of this approach to seakeeping problems of some real hull form ship has been described and comparison with experimental & numerical results given by 2-D & semi 3-D methods demonstrates that this 3-D near field approach is valid in predicting added resistance of ship and also provides better results in many cases particularly for blunt shaped slow speed vessel.