The Motion Analysis Program Suite (MAPS) has been developed at Memorial University of Newfoundland based on the panel-free method for the accurate computation of wave-body interactions in the frequency domain. In the panel-free method, the desingularized integral equation in terms of source strength distribution is developed by removing the singularity due to the Rankine term in the Green function. NURBS surfaces are adopted to describe the exact body geometry mathematically. The integral equations are discretized over the body surface by Gaussian quadratures. In this work, computations by the panel-free method have been extended to floating bodies with complex geometry. Validation studies are presented for a Liquefied Natural Gas (LNG) carrier in shallow water and a Floating Production Storage and Offloading (FPSO) vessel in deep water. Results are compared with experimental data and those by the panel method.
The panel method has been widely used in the computation of ship and offshore structure responses in waves. Hess and Smith (1964) pioneered the panel method in which the body surface was subdivided into flat quadrilaterals. The integration of the singular 1/r term over a panel was obtained by assuming that the panel is planar quadrilateral or triangle with the constant source strength distribution. It is often referred as the constant-source-flat-panel method or a lower-order panel method. Normally, a large number of panels are required to achieve accurate results. For bodies with complex geometry, it is challenging to develop a panel generator for practical applications. Higher-order panel methods have been developed in various degrees to overcome the deficiencies of the constant-source-flat-panel method. Most higher-order methods allow for linear or quadratic panels and first- or second-degree polynomial distribution of source strength over a panel. It normally requires more computational effort than the lower-order panel method.