TIDAL SIMULATION OF A BAY WITH A VERY LARGE FLOATING
STRUCTURE USING A MULTI-LEVEL MODEL
C.H. Hu and Y, Kyozuka, Department of Earth System Science and Technology, Interdisciplinary Graduate School of Engineering Science, Kyushu University, Kasuga, Japan
ABSTRACT
Accurate tidal flow simulation is necessary for environmental assessment of a large-scale ocean development in a bay, because the flow plays an important role in mass-transport and other physical phenomena.
In this paper we present a method to simulate tidal flows of a bay with a very large floating structure using a multi-level model. Pressure under the pontoon-type floating structure is obtained by solving the Poisson equation. Effects of vertical displacement of the pontoon due to tidal force are considered in the tidal simulation.
Tidal currents, residual currents and wind driven currents in a bay with/without the structure are presented graphically and discussed.
NONLINEAR DIFFRACTION OF WAVES BY A SUBMERGED SHELF IN SHALLOW WATER
R.Cengiz Ertekin and Janet M. Becker, Department of Ocean Engineering, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa, 2540 Dole Street,
Holmes Hall 402, Honolulu, HI 96822, USA
ABSTRACT
The diffraction of water waves by submerged obstacles in shallow water generally requires the use of a nonlinear theory since both dispersive and nonlinear effects are important. In this work wave diffraction is studied in a numerical wave-tank using the Green-Naghdi (G-N) equations. Cnoidal waves are generated numerically by a wave maker situated at one end of a 2-dimensional numerical wave tank At the down wave end of the tank an open-boundary condition is implemented to simulate a wave-absorbing beach and thus to reduce reflections. The G-N equations are solved in the time-domain by employing a finite-difference method. The numerical method is applied to diffraction of cnoidal waves by a submerged shelf, o ra sand bar, of considerable height relative to water depth.
The predicted results are compared with the available experimental data which indicate the importance of nonlinearity for the shallow-water conditions.
