Slow Drift-Oscillations of a Ship in Irregular Waves

• Main Authors: Odd M. Faltinsen, Arne E. Løken
• Format: Article
• Language: English
• Published: Norwegian Society of Automatic Control 1980-10-01
• Series: Modeling, Identification and Control
• Subjects: Hydrodynamics; slowly varying wave forces; wave drift forces; strip theory; mooring
• Online Access: http://www.mic-journal.no/PDF/1980/MIC-1980-4-1.pdf

A procedure to calculate horizontal slow drift excitation forces on an infinitely long horizontal cylinder in irregular beam sea waves is presented. The hydrodynamic boundary-value problem is solved correctly to second order in wave amplitude. Results in the form of second order transfer functions are presented for different, two-dimensional shapes. It is concluded that Newman's approximative method is a practical way to calculate slow drift excitation forces on a ship in beam sea and it is suggested that it may be used in a more general case. Applications of the results for moored ships are discussed.