MULTILAYER MODELING OF 3-DIMENSIONAL HYDRODYNAMIC TRANSPORT PROCESSES

A multi-layer water-sediment predictive model has been developed to st udy the effects of coastline reconfigurations on the three-dimensional (3-D) flow and sediment fields in coastal waters. The model is gridde d with finite elements in the horizontal domain for easy adaptation to complex boundary configurations. The non-uniformity of flow and sedim ent distributions in the water column are represented by multiple vert ically averaged layers. The Lax-Wendroff two-step scheme is used for t ime marching. This allows the flow field and sediment field to be expl icitly coupled so that the density of the water-sediment mixture and t he flow depth are updated without matrix inversion for the advanced ti me level. Because of the adoption of the explicit time-marching scheme , the allowed time increment of the present numerical scheme is relati vely small. However, this is beneficial to studying short life activit ies such as sediment entrainment and deposition. The model predicted r esults were tested against field measurements in two case studies and good agreement was found in each case.