An Integrated Numerical Approach for Coastal Engineering Problems
Keywords:Numerical models, boundary conditions, waves, sediment transport, shoreline evolution, breaker zone, hydrodynamics
This paper presents a system that is capable of generating numerical models for water and sediment motion, in which the level of precision is defined by the accuracy of initial and boundary data. This provides a simulation in which the coat is concordant not only with the amount and precision of available input information but also with the general objectives of the project. The system is divided into three units: (i) wave/current propagation, (ii) nearshore circulation and (iii) shore-line evolution. Unit (i) is composed of two models of which the first is based on linea (sinusoidal) theory and valid only for wave refraction. The second model uses a rather general set of mass and momentum conservation laws and is able to reproduce wave and current propagation, including their mutual interactions together with the effects of refraction, diffraction and reflection. An original absorbing-reflecting boundary condition is also presented. This condition, apart from being more accurate for 2D flow than most of the state-of-the art conditions, is also more general, allowing a unified treatment for all boundaries. Unit (ii) is made up of two modules. The first, based on analytical solutions for wave decay and longshore flow, is used for alongshore uniform problems. The second is based on mass and momentum conservation equations (including radiation stresses), using vertical and across shore integration. This technique, developed here to allow an efficient calculation of set-up and transverse and alongshore velocities for a varying coast-line, provides hydrodynamic information with the precision level required by bulk formulations for sediment transport. These formulations are the basis of unit (iii) which, at the moment includes only a 1-line shoreline evolution model. This model is able to reproduce the effect of the most usual coastal works (perpendicular groynes, detached breakwaters, etc.).