SHIP'S BOW MOTION PREDICTION ACCURACY INCREASED USING SECOND-ORDER THEORY
Predicting ship heave and pitch motions by a second-order theory has been documented in a report published at the David Taylor Naval Ship R&D Center, Bethesda, Md. The newly developed theory represents an improvement over linear ship-motion theories that assume that ship displacements are small relative to ship dimensions and that the body-boundary condition can be satisfied at the mean undisturbed position of the hull. These conditions are violated by the bow motions of most ships, even in moderately steep head waves, and the consideration of second-order effects will provide increased prediction accuracy in relative bow motions, important in predicting deck wetness and slamming. Under assumptions of the second-order theory, it is shown that the equations governing the motions consist of two sets of coupled equations. One set is identical to the existing conventional strip theory, and another set contains second-order terms which are products of the first-order motions and hydrostatic-restoring and Froude-Krilov forces. It has been shown that the hydrodynamic problems associated with added mass, damping, and diffraction must be solved only to the first order of accuracy with respect to wave slope.
Navy Technology Transfer SheetCode E411, Naval Surface Weapons Center
Dahlgren, VA United States 22448
- Publication Date: 1979-7
- Pagination: n.p.
- Volume: 4
- Issue Number: 7
- TRT Terms: Bows; Decks (Ships); Pitch (Dynamics); Ship motion; Slamming
- Uncontrolled Terms: Heaving
- Old TRIS Terms: Bow motions; Deck wetness; Heave response
- Subject Areas: Marine Transportation; Vehicles and Equipment;
- Accession Number: 00197067
- Record Type: Publication
- Files: TRIS
- Created Date: Aug 28 1979 12:00AM