This paper presents the description of a higherorder boundary element method (HOBEM) for calculating linear hydrodynamic loadings on large floating bodies and comparison with constant panel methods and HOB EMs that are employed in conjunction with the hybrid boundary integral equation procedure, for a variety of structural configurations. It was concluded from the study that HOB EM has several important features: it uses many fewer boundary elements and much less computer time, with higher accuracy than conventional methods. In addition to these, the computer code for hydrodynamic loadings can easily be used for finite element structural analysis.
Reliable estimates of the hydrodynamic loadings on large offshore structures are critical in the assessment of structural response, stability and fatigue life. The constant panel method (CPM) introduced by Hess-Smith (1964) has been widely used for calculating hydrodynamic loadings, for example by Faltinsen-Michel sen (1974); Garrison (1979); InglisPrice (1980); Ostergaard-Schell in (1987); and Korsmeyer et al. (1988). In the constant panel approach, the surface of a three-dimensional body is replaced by quadrilateral or triangular facets. Each facet (or panel) represents a source distribution of constant strength with satisfaction of a Newmann boundary condition required at the center (control point) of each panel. Consequently, the constant panel approach has several limitations:
the source distribution is discontinuous, i.e., the source strength is constant over each panel and jumps stepwise at the boundary of neighboring panels;
for curved body surfaces, the quadrilaterally faceted surface becomes discontinuous as all the four corner points generally do not coincide with those of the neighboring panels. Thus, the faceted surface introduces so-called "leaks". To overcome the foregoing limitations, Webster (1975) proposed the use of triangular panels with linear source distributions located just beneath the actual body surface.