Abstract: A numerical model was developed for simulating a three-dimensional multilayer hydrodynamic and thermodynamic model in domains with irregular bottom topography. The model was designed for examining the interactions between flow and topography. The model was based on the three-dimensional Navier-Stokes equations and was solved using the fractional step method, which combines the finite difference method in the horizontal plane and the finite element method in the vertical plane. The numerical techniques were described and the model test and application were presented. For the model application to the northern part of Ariake Sea, the hydrodynamic and thermodynamic results were predicted. The numerically predicted amplitudes and phase angles were well consistent with the field observations
Abstract: The development of a numerical model using the fractional area/volume obstacle representation (FAVOR) method for predicting a nearshore current field bounded by complicated geometric shapes, and a three-dimensional (3D) beach evolution was described in this article. The 3D model was first tested against three cases to simulate the nearshore current fields around coastal structures, a river mouth, and a large scale cusp bathymetry. Then, the morphodynamic model tests, which are adopting the nearshore current model, were applied for the computations of beach evolution around a detached breakwater and two groins. It was confirmed that the presented model associated with the FAVOR method was useful to predict the nearshore current field in the vicinity of the complicated geometric shapes. Finally, the model was applied to a tombolo formation in a field site of Kunnui fishery port, which is located in Hokkaido, Japan.
Abstract: This article describes the development of a three-dimensional (3D) multilayer hydrostatic model of tidal motions in the Ariake Sea and its application. The governing equations were derived from 3D Navier-Stokes equations and were solved using the fractional step method, which combines the finite difference method in the horizontal plane and the finite element method in the vertical plane. This study introduced a 3D, time-dependent, hydrostatic, tidal current model that can compute wetting and drying in tidal flats due to tidal motion. The 3D model was first tested against analytical solutions for three standard cases in a rectangular basin in order to investigate the performance of the model. Then, the model was applied to Saigo fishery port and the Ariake Sea. For standard cases, the numerical solutions were almost identical to the analytical solutions. Finally, the model results for Saigo port and the Ariake Sea show good agreement with the field observations.
Abstract: A new development of a three dimensional (3D) multi-layer wind-induced circulation model of Ariake Sea region is described in this paper. The hydrodynamic equations are derived from 3D Navier Stokes equations and solved using the fractional step method (FSM). The 3D hydrodynamic model is first tested against analytical solution in order to investigate the performance of the model. And then, it was applied to the Ariake Sea. For model test, the numerical results are almost identical to the analytical solutions. It was shown that the numerical model developed was capable to simulate wind-induce flows in shallow semi-enclosed/enclosed waters.
Abstract: This paper focuses on the sensitivity analysis of various design parameters for heavy-duty
pavement for container terminal areas using Airport Pavement Structural Design System (APSDS) to yield an optimal design solution. APSDS is based on layered elastic theory, which was introduced into airfield design practice with the release of the computer program LEDFAA (Layered Elastic Design, Federal Aviation Administration). In this study, the effects of lateral wandering distribution, container weight frequency, design life, variation of elastic modulus for concrete block pavers and sub-grade, changing the handling system, and changing the interface conditions at the bottom of base layer on the pavement design were carried out. Also various construction materials were used and several combinations of base and subbase
materials were analysed to be able to select the most economical pavement structures.
Abstract: A high spatial resolution forecasting system for ocean current in the Japan/East Sea (JES) was proposed. The proposed forecasting system consists of three steps, which are the current field computations of the whole area of the JES, the intermediate area and the near-shore area. The current field in the area of JES was firstly computed by the RIAM model, and then the intermediate and near-shore areas were computed by the MEC model. Furthermore, particle tracking experiments using the Euler-Lagragian tracking method were performed. The proposed system was applied to the western part of Japan/East Sea including Tottori coast, and the validity of the forecasting system was investigated.
Abstract: The techniques for protecting sandy beach have been changed from âhard engineeringâ using the coastal structures into âsoft engineeringâ such as sand nourishments. The sand nourishment is not only an effective technique for recovering eroded beaches but also for maintaining the ecological environments. In general, the nourished materials are injected near shoreline. The nourishments near shoreline effectively act to recovery of the eroded beaches. However, in case that there are some problems such as transportations and costs, sediments are injected in offshore area within critical water depth. Recently, the offshore nourishment such as shoreface nourishment (e.g. van Duin et al., 2004; Grunnet and Ruessink, 2005; Ojeda et al., 2008) has been employed to improve the coastal stability. Although the shoreface nourishment did not directly contribute the shoreline advances, however, the nourishment effectively acted as a submerged breakwater to reduce the high wave and to control the nearshore currents behind the nourished area (van Duin et al., 2004).
To evaluate the effect of the sand nourishment such the shoreface nourishment, a predictive model is required. Although some models based on N-Line model (e.g. Hanson et al., 2000; Uda et al.,2004; Shibutani et al., 2008) have been proposed, it seems to be difficult for applying the complicated bathymetry changes such as the rip-channel and offshore bar. Therefore, the 3D model so called coastal area model (e.g. de Vriend et al., 1993; Lesser et al., 2004) may be effective to the complicated bathymetry changes.
The purpose of this study is to develop a numerical model that can predict 3D morphodynamics after offshore sand nourishment such as the shoreface nourishment. In this study, the previous model presented by Kuroiwa et al. (2004, 2008) is modified to be capable to simulate the nourishing process of sand and the 3D morphodynamcs after the nourishment. A model test associated with offshore nourishment is carried out. Furthermore, the applicability of the presented model to field site is investigated.
Abstract: This article describes the development and application of a three dimensional (3D) multilayer hydrodynamic model of tidal motions and thermohaline circulation. The governing equations were derived from 3D Navier-Stokes equations and were solved using the fractional step method, which combines the finite difference method in the horizontal plane and the finite element method in the vertical plane. The 3D model was first tested against the density current test in order to investigate the performance of the model. Then, the model was applied to the northern part of the Ariake Sea. In the model test, the results of density current were agreed qualitatively with the performance of salt intrusion. In the model application, the hydrodynamic and thermohaline circulation are
predicted. The computed amplitudes are agreed within ±3% compared with the observations, and the phase angles agreed well with the observations. The phase angle results were improved when the thermohaline circulation was considered in the computations as compared with the results without the thermohaline consideration. The tidal currents for the Ariake Sea form a round-trip style during the flood and ebb tides. The numerically predicted results show good agreement with field observations of tidal currents, and they improved after considering the thermohaline circulation.
Abstract: This paper presents a new three dimensional (3D) tidal current model that can compute wetting and drying bed (WAD) in tidal flats due to tidal motion. The governing equations are derived from 3D Navier Stokes equations and solved using the fractional step method (FSM), combining the finite difference method in the horizontal plane and the finite element method (FEM) in the vertical plane. First, a model test for Saigo fishery port was carried out in order to investigate the
performance of the model. Secondly, the tidal currents with the WAD in the north bay of Ariake Sea were simulated. Finally, the applicability of the model was discussed.
Abstract: This paper describes the development and application of a three dimensional (3D) multilayer
hydrodynamic model to tidal motions in Ariake Sea. The governing equations are discretized into finite difference horizontally and finite element vertically in a uniform staggered grid system. The velocity components in the x, y, and z directions are directly obtained. Our study introduces a new 3D, time-dependent, non-hydrostatic, tidal current model that can compute wetting and drying bed (WAD) in tidal flats due to tidal motion.
The 3D model is tested for artificial tidal flat surrounded by breakwaters in order to investigate the performance of the presented model. The model results for the velocities and the free surface water elevations coincide with observation for Saigo Port (Abualtayef et al., 2006). Then, the model is applied to the Ariake Sea. In the first simulation, the tidal current behavior including current circulation and time history of sea levels is predicted. The numerically predicted results show good agreement with field observations.
Abstract: In this research, the development and application of a three-dimensional multi-layer hydrodynamic and thermohaline circulation model are documented. The governing equations are derived from the three-dimensional Navier-Stokes equations for incompressible free surface flows. The algorithm is based on the fractional step method. The solution is obtained in subsequent stages and the equations were split into parts using well-defined mathematical properties, so that the most adequate methods for a given differential operator type can be used. The fractional step method is combining the finite difference method in the horizontal plane and the finite element method in the vertical plane. The computational domain variability is taken into account by a staggered grid structure, which is well suited to most geophysical applications. This study introduces a three-dimension, a time-dependent, hydrodynamic, tidal- and density-currents model that can compute wetting and drying in tidal flats due to tidal motion. The free surface position can be found using a height function method based on the free surface conservative equation. In the numerical solution algorithm, the Galerkin finite element method with an explicit formulation was used.
The developed model has been verified using a number of benchmark test cases covering the targeted model application domain in order to investigate the performance of the model. Some of these cases allow a formal comparison with an analytical problem solution. They include wind-driven currents, tide-driven currents, and free surface elevation. The numerical solutions are almost identical to the analytical ones.
The model applications to Saigo fishery port and Ariake Sea have been carried out at first. Then, the model has been applied to the northern bay of the Ariake Sea to simulate the tidal- and density-currents, and thermohaline circulation. The model results for Saigo port and Ariake Sea show good agreement with the field observations. In the hydrodynamic model, the tidal- and density-currents behaviors including current circulation and time history of sea levels are predicted. The numerically predicted results show good agreement with available field observations of tidal currents and water levels.
Abstract: Several mechanical and empirical design methods for heavy-duty pavements have been compared. For flexible pavements the British Port Associations method, the Spanish design method, and the Australian design method have been used. For rigid pavements the Dutch design method using the VENCIN program and the Spanish design method were used.
The advantages of mechanical design methods are as follows:
ï±Possibility to determine the location of critical points in the pavement structure, where the damage will occur, and how it will spread;
ï±The effect of changing materials and load characteristics can easily be assessed;
ï±Possibility to enhance understanding into the behaviour of pavements;
ï±A fair estimate of the pavements design life can be made; and
ï±They allow assessment of the effect if specifications are not met.
This study focuses on determining optimum thickness for all pavement layers made by local available construction materials and different loading conditions for the container terminal area and Multi-purpose terminal at Port of Gaza.
Furthermore this research focuses on the effects and the sensitivity of lateral wandering distribution, container weight frequency, design life, variation of elastic modulus for both concrete block pavers and sub-grade, changing the handling system, and changing the interface conditions at the bottom of a base layer.
The computer programs based on the mechanical approach shows the capability of providing the pavement engineer with powerful new tools for studying a wide range of particular pavement materials and sub-grades. They are also capable to model accurately under complex loading conditions.
It is recommended to use the mechanistic approach to yield an optimal design solution. However, one has to be careful with calculations based on assumed general adopted mechanical characteristics expected for certain types of material and the way these materials are applied.
Overall the objectives of this study have been met and the recommendations to design an economical and structurally sound port pavement have been formulated.
