Hydrodynamic reaction to large amplitude rolling motion

Article type: Research Article

Authors: Yücel Odabaşi, A.

Affiliations: The British Ship Research Association, Wallsend, England

Abstract: In this paper an attempt is made to evaluate the possibility of extending the ad hoc lateral ship motions theory to the large amplitude rolling motion analysis. To gain a better insight, the problem is first posed within small amplitude restrictions (i.e. linear) with viscosity included and it is shown that the assumption on the separability of different contributions is not correct and the concept of added mass and damping in a viscous fluid are not well-understood. Contributions from the bilge keels are treated separately in a similar manner to the wing-body problems in aeronautics as opposed to the very low aspect ratio approach proposed by Schmitke [5]. Next the features of the large amplitude rolling motion of a ship as a non-linear system is discussed and the essential differences between this and the linear systems are high-lighted. Some suggestions on the possible method of approach are also discussed. Having completed the examination of analytical methods, attention is paid to the experimental procedures and data in the light of the scaling laws and dimensional analysis and it is shown that almost all of the reported experiments do not comply with the scaling laws since no attempt has been reported to derive them for the non-zero forward speed case. Some suggestions are made on possible future work on both the analytical and the experimental sides.

DOI: 10.3233/ISP-1981-2832001

Journal: International Shipbuilding Progress, vol. 28, no. 320, pp. 74-82, 1981