The system of integro-differential equations, which combines long wave nonlinearity with full linear dispersion, is presented as new model equations for studying nonlinear evolution of shallow water waves. The dispersion term is represented by an integral with the kernel of the Fourier transform of phase velocity. Among the nonlinear wave equations developed from the system for spectral-wave components, the simplified version is applied to waves over the step-type reef in two-dimensions. Comparisons between present numerical results and experimental data are made. The results show that there occurs modulation chiefly in the amplitude and the phase of the first harmonic because of nonlinear interaction between wave components and bathymetry of the reef. Consequently, there may be the resonance of incident waves on the step-type reef due to vertical bathymetric variation.41 Coast. Eng. J. 1998.40:41-60. Downloaded from www.worldscientific.com by UNIVERSITY OF CALIFORNIA @ SAN DIEGO on 08/18/15. For personal use only. Coast. Eng. J. 1998.40:41-60. Downloaded from www.worldscientific.com by UNIVERSITY OF CALIFORNIA @ SAN DIEGO on 08/18/15. For personal use only.
One of the important procedures for Disaster Prevention Plan is to determine accurately the wind condition of an approaching typhoon. By using the Meteorological Model, it enables the aforementioned situation to be specified. The purpose of this study is for the method application to the Disaster Prevention Plan. The effect examined is due to the difference of several computational condition by Typhoon 5115. This reveals the property model of WRF with Typhoon Bogus. In addition to that, we enumerated the problem issued from the model utilization in order to make the application easy. According to the study, it is proved that the parameters of Rb and Ro greatly influences reproducibility of typhoon. The magnitudes of central pressure and wind velocity speed are susceptible to Nudging coefficient .
Storm surges and high waves occur at the same time. Due to high tide and waves, water overflow and wave overtopping occur over the coastal levee. Numerical simulation based on the two-dimensional Navier-Stokes equations by using the VOF method, CADMAS-SURF, is applied. The overflow and overtopping calculated by numerical simulation is analyzed, the hydraulic characteristics of flow rate over the coastal levee are clarified.Keywords: storm surge, high waves, coastal levee, overflow, overtopping, N-S simulation, flow rate
INTRODUCTIONThe risk of inundation disaster by storm surge with high waves increases recently with sea level rise and intensified typhoon activity caused by global warming. When typhoons attack on the coast, storm surges and high waves occur at the same time. Due to high tide and waves, water overflow and wave overtopping occur over the coastal levee. At the time of storm surge, the inundation disaster is induced by combination of wave overtopping and water overflow.Against the overflow and overtopping occur at the same time, it is difficult to measure the flow rate over the coastal levee by hydraulic experiments and field observations. The estimation method of transition process from overtopping to overflow has not been established so far. The applicability of inundation simulations by storm surge depends on the accurate estimation of the flow rate over the coastal levees induced by both overtopping and overflow.Therefore, numerical simulation based on the two-dimensional Navier-Stokes equations by using the VOF method, CADMAS-SURF, is applied. By this simulation, flow rate over the coastal levee is clarified. The flow rate is compares with the formulas of overflow and overtopping base on the hydraulic experiments. In this study, numerical simulations about water overflow and wave overtopping are performed. The overflow and overtopping calculated by numerical simulation is analyzed, the hydraulic characteristics of flow rate over the coastal levee are clarified. Fig. 1 is schematic diagrams of the transition process from wave overtopping to water overflow. When h c /H 0 '>0.5, overtopping rate can be estimated by using the Goda's diagrams (1975). When h c /H 0 '<0.0, h c =-h 1 , the water level is slightly higher than the dike crest. Flow rate is underestimated by using the overflow formula. When -0.5
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