Can a single floating body be expressed as the sum of two bodies?

Journal of Engineering Mathematics (Impact Factor: 0.8). 10/2010; 68(2):153-164. DOI: 10.1007/s10665-010-9387-7

ABSTRACT Can a single floating body be expressed as the sum of two bodies? Geometrically, the answer is always ‘yes’. However, the
subject of the present paper is if this is also the case from the viewpoint of hydrodynamics, that is, (1) if it is justified
to treat hydrodynamic-interaction theory as if there exists some water between the two opposing surfaces of the two bodies,
although actually no water exists between them? and (2) can the wave field around one of the two bodies due to the waves scattered
by the other body be expressed in terms of a local coordinate system fixed to the corresponding body and vice versa? Theoretical
and numerical investigations are carried out and it is concluded that the answer to the first question is ‘yes’, whereas the
answer to the second question is, in principle, ‘no’, but, in practice, such integrated quantities as hydrodynamic forces,
especially horizontal forces, could still be calculated quite correctly if the body is divided into rectangular sub-bodies
with aspect ratio close to unity.

KeywordsAddition theorem of Bessel functions-Hydrodynamic interaction-Very large floating structure

9 Reads
  • [Show abstract] [Hide abstract]
    ABSTRACT: Two-dimensional waves are incident upon a pair of vertical flat plates intersecting the free surface in a fluid of infinite depth. An asymptotic theory is developed for the resulting wave reflexion and transmission, assuming that the separation between the plates is small. The fluid motion between the plates is a uniform vertical oscillation, matched to the outer wave field by a local flow at the opening beneath the plates. It is shown that the reflexion and transmission coefficients undergo rapid changes, ranging from complete reflexion to complete transmission, in the vicinity of a critical wavenumber where the fluid column between the obstacles is resonant.
    Journal of Fluid Mechanics 10/1974; 66(01):97 - 106. DOI:10.1017/S0022112074000085 · 2.38 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We consider three-dimensional water-wave diffraction and radiation by a structure consisting of a number of separate (vertically) non-overlapping members in the context of linearized potential flow. An interaction theory is developed which solves the complete problem, predicting wave exciting forces, hydrodynamic coefficients and second-order drift forces, but is based algebraically on the diffraction characteristics of single members only. This method, which includes also the diffraction interaction of evanescent waves, is in principle exact (within the context of linearized theory) for otherwise arbitrary configurations and spacings. This is confirmed by a number of numerical examples and comparisons involving two or four axisymmetric legs, where full three-dimensional diffraction calculations for the entire structures are also performed using a hybrid element method. To demonstrate the efficacy of the interaction theory, we apply it finally to an array of 33 (3 by 11) composite cylindrical legs, where experimental data are available. The comparison with measurements shows reasonable agreement.
    Journal of Fluid Mechanics 04/1986; 166(-1):189 - 209. DOI:10.1017/S0022112086000101 · 2.38 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: New numerical methods are presented for hydroelastic analyses of a very large floating structure (VLFS) of several kilometers length and width. Several methods are presented that accelerate computation without an appreciable loss of accuracy. The accuracy and efficiency of the proposed methods are validated through comparisons with other numerical results as well as with existing experimental results. After confirming the effectiveness of the methods presented, various characteristics of the hydroelastic behavior of VLFSs are examined, using the proposed methods as numerical tools.
    Journal of Marine Science and Technology 11/1999; 4(3):123-153. DOI:10.1007/s007730050015 · 0.81 Impact Factor


9 Reads
Available from