一般注記A novel ship concept which is called ULBS (Ultra Large Block coefficient ship) to reduce CO2 emission form sea transportation is under investigation at Yokohama National University. Since ULBS is supposed to have a very blunt hull, flow field analysis around a ship is crucial for a design of hull forms with better hydrodynamic performance. Computational Fluid Dynamics (CFD) is expected to be an efficient design tool for unconventional hull forms such as ULBS. However, it is desirable to examine applicability of the CFD method to analysis of similar flows before the actual design application. Thus, free surface flow computations of two box-shaped ships which can be considered as the extreme cases of ULBS are carried out. Grid convergence study is performed with respect to resistance for the verification of the results. Total resistance coefficients are compared with each other and also with available experimental data. The pressure and velocity distributions of the two ships are compared with each other. The flow structures with large separations are observed and the influences of the box geometry to the flow fields are discussed. This knowledge is used in the computation of ULBS. After that to investigate the flow characteristics of ULBS (Cb>0.95), free surface viscous flows around the ship with and without a stern tunnel are computed by the solver. Total resistance coefficients are compared with each other and with experimental data. The pressure and velocity distributions of the two ships are compared with each other. Also, grid convergence study is performed with respect to resistance for the verification of the results. The velocity distributions behind the stern of the two ships are compared with each other. The three dimensional vortical structures in the stern of the two hulls are analyzed and compared with each other. Massive flow separations behind the stern due to the bluntness of a hull and effects of a stern tunnel to flow fields are discussed and this knowledge will be used on the future design of ULBS.
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受理日（W3CDTF）2016-08-04T09:59:51+09:00
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