Taro Kakinuma

Surface and Internal Waves due to a Moving Load on a Very Large Floating Structure

Interaction of surface/internal water waves with a floating platform is discussed with nonlinearity of fluid motion and flexibility of oscillating structure. The set of governing equations based on a variational principle is applied to a one- or two-layer fluid interacting with a horizontally very large and elastic thin plate floating on the water surface. Calculation results of surface displacements are compared with the existing experimental data, where a tsunami, in terms of a solitary wave, propagates across one-layer water with a floating thin plate. We also simulate surface and internal waves due to a point load, such as an airplane, moving on a very large floating structure in shallow water. The wave height of the surface or internal mode is amplified when the velocity of moving point load is equal to the surface- or internal-mode celerity, respectively.

19. NUMERICAL ANALYSIS OF HARBOR OSCILLATION IN HARBORS OF VARIOUS SHAPES

A numerical model based on nonlinear shallow water equations is applied to study oscillations in harbors of various shapes including L-type harbors, I-type harbors with a narrowed area, a C-type harbor, a T-type harbor, and I-type harbors with a seabed crest or trough. The second mode shows a higher amplification factor at the head of an L-type harbor as its bending position is nearer to the harbor mouth. As a narrowed area of an I-type harbor is located nearer to the harbor mouth, amplification factors of the first and second modes at the harbor head are lower and higher, respectively. A C-type harbor shows rather complicated amplification because the phase difference between waves propagating through two harbor mouths depends on the position inside the harbor. The oscillation in an actual bay, i.e., Urauchi Bay, which has a shape similar to that of a T-type harbor, is also numerically simulated; damping processes are compared between Urauchi Bay and a T-type harbor.