Erosion Control of Scour during Construction. Report 6. FINITE - A Numerical Model for Combined Refraction and Diffraction of Waves.

Abstract : It is frequently necessary to construct large engineering works of improvement in the surf and nearshore zone to protect harbor entrances, navigation channels, etc. These structures are placed in position by crane or barge. When these major structures are erected in the coastal zone they alter the existing currents. Shallow-water surface gravity waves breaking on the new structure will cause bottom material to be suspended and transported from the region by longshore or other currents that may exist. Since removal of material is often not compensated by an influx of additional material, the result is a scour hole, or erosion, that usually develops along the toe of the structure. A hybrid finite element numerical model (FINITE) is presented that solves a linear mild-slope equation for short-wave propagation. The efficient formulation of the model permits the solution of large problems with relatively small time and memory storage requirements. Although the model solves an equation that is strictly valid only for mild bathymetric variations, can provide reasonable answers for problems where there are rapid depth variations (at much lower cost than required by three-dimensional models that are appropriate for problems involving rapid depth variations). The model does not provide a mechanism for energy dissipation, and thus energy loss through wave breaking is simulated by permitting waves to propagate out of the computational region. Program documentation, user guide, and sample problem output, are provided.