波浪中を航走する双胴船の双胴間干渉流体力の研究 : その1 Radiation問題

概要

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A new theory is presented of predicting hydrodynamic forces on a catamaran heaving and pitching with forward speed. The theory is based on Newman's unified slender-ship theory and regarded as an extension of the study on tank-wall interaction effects made by the present author to the interaction problem between twin hulls ; thus the theory is valid over a wide range of forward speeds including zero, and the computation is of relative ease. The inner region is defined as the vicinity of one of the twin hulls and hence the inner solution includes not only symmetric but also asymmmetric homogeneous components. The matching requirement between the inner and outer solutions gives a coupled integral equation for the strength of 3-D source and doublet distributions in the outer solution, and its numerical solutions determine the unknown coefficients of inner homogeneous components. Excellent agreement is shown for the zero-speed case between the present theory and a more rigorous 3-D integral-equation method. For the forward-speed case, the forced oscillation tests of heave and pitch are conducted using twin Lewis-form ships at Fn=0.15 and 0.3. Comparison of these results with numerical computations shows that the present theory provides a sizable improvement over the conventional strip method incorporating 2-D exact interaction solutions in accounting for 3-D and forward-speed effects upon the interaction between twin hulls.