Hydrodynamic Modelling of Offshore Floating Structure Incorporating Viscous Dissipation Effects

This paper introduces a new feature to the OREGEN-BEM program—a dipole element—which enables consideration of the velocity discontinuity across the two sides of a thin plate. A modified potential flow model incorporating viscous dissipation effects is developed, and the corresponding boundary integral equations are derived to include integrals over both the body surface and the dissipative surfaces. This enhancement allows accurate hydrodynamic modelling of thin plates, such as the oscillating surge wave converters and floating structure with a heave plate, where the flap thickness or heave plate thickness is small compared with the wavelength, capturing the velocity jump across the two sides of a perforated flap. Moreover, it can effectively simulate offshore structures with dissipative perforated plates. To the best of our knowledge, this is the first open-source implementation of a dipole element in the field of ocean engineering, distinguishing OREGEN-BEM from other open-source boundary element codes such as HAMS and NEMOH. The newly developed OREGEN-BEM with the dipole element feature is first validated against the published experimental data for an offshore floating wind turbine with a thin thickness dissipative plate. Finally, it is then applied to optimal choosing the suitable diameter of bottom disk.