Tham khảo tài liệu 'mechanical engineers reference book 12e episode 13', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Dynamics of floating systems 14 31 linearity around resonance with the heave response amplitude per unit wave amplitude reducing from m m at 1 m wave amplitude to m m at 6 m wave amplitude. The vessel motion response away from resonance is not significantly affected although there is some increase in response around 16-19 s due to the corresponding increase in wave force amplitude at these periods. The large change in the unit heave response at and around resonance is to be expected since the damping force in a vibratory system is dominant at resonance. Diffraction theory Calculations of wave-induced motions of a large non-space frame structure in gravity waves requires a solution of the W ave problem with no flow boundary conditions at the moving body surface in addition to the free surface and sea-bed boundary conditions. The solution can be split into two related problems - the scattering wave problem defines wave forces on a floating body when fixed in space and with waves incident on it in an identical manner to the technique for computing wave forces on a fixed body described in Section . The radiation wave problem is concerned with defining forces on the body added mass and damping due to its oscillation in otherwise still water. These oscillations will induce wave potentials such that the total wave potential in the fluid is the sum of the incident 6W scattered j 5 and forced wave potentials bf so that Ỏ ộw b dy and these must satisfy the boundary conditions at the bodysurface given by dn dn Sn where V. is the velocity of the body surface in the direction n normal to the surface. This boundary condition can be applied at the mean body surface since the theory is applied for small motions. t together with its three components. It must also satisfy the Laplace equation and the free surface and sea-bed boundary conditions. Furthermore t s and t f must satisfy the radiation conditions. Boundary conditions for the scattering and
