
Accession Number : AD0692507
Title : A RATIONAL STRIP THEORY OF SHIP MOTIONS: PART I.
Descriptive Note : Interim technical rept. 1 Nov 6828 Feb 69,
Corporate Author : MICHIGAN UNIV ANN ARBOR DEPT OF NAVAL ARCHITECTURE AND MARINE ENGINEERING
Personal Author(s) : Ogilvie,T. Francis ; Tuck,Ernest O.
Report Date : 01 MAR 1969
Pagination or Media Count : 105
Abstract : The exact idealfluid boundaryvalue problem is formulated for a ship forced to heave and pitch sinusoidally in otherwise calm water. This problem is then simplified by applying three restrictions: (1) the body must be slender; (2) the motions must be small in amplitude compared with ship beam or draft; (3) the frequency of oscillation must be high. The hydrodynamic problem is then recast as a singular perturbation problem which is solved by the method of matched asymptotic expansions. Formulas are derived for the hydrodynamic heave force and pitch moment, from which addedmass and damping coefficients can be easily obtained. The latter are similar but not identical to those used in several other versions of 'strip theory;' in particular, the forwardspeed effects have the symmetry required by the theorem of Timman and Newman, a result which has not been realized in previous versions of strip theory. In order to calculate the coefficients by the formulas derived, it is necessary to solve numerically a set of boundaryvalue problems in two dimensions, namely, the problem of a cylinder oscillating vertically in the free surface. At least two practical procedures are available for this purpose. (Author)
Descriptors : (*SHIPS, *HYDRODYNAMICS), EQUATIONS OF MOTION, THEORY, BOUNDARY VALUE PROBLEMS, PITCH(MOTION), OSCILLATION, MOMENTS
Subject Categories : Marine Engineering
Fluid Mechanics
Distribution Statement : APPROVED FOR PUBLIC RELEASE