Study of the diffusion activity in case of non-breaking waves with a current

Sediment transport causes morphological changes of coastal areas, and it is one of the most important objects in coastal engineering study. Recently, various experiments have been performed to investigate the sediment transport mechanism under a combination of waves and currents and to find the underlying relationships among various parameters which control the sediment transport mechanism is a main topic of research. But still there are many unknown and unexpected facts in this phenomenon. Therefore, further efforts to investigate the basic mechanism of this phenomenon is inevitable. The diffusion coefficient which expresses the intensity of the diffusion activity is one of the most important parameters controlling this phenomenon. In this report, two different approaches to estimate the diffusion coefficient in case of ,non-breaking waves with a current are discussed. The first one is based on the concentration distribution, and the second one is based on the velocity distribution. For these approaches. the experimental data measured by E.N.Nap and H.F.A.van Kampen (August 1988 TU Delft) are mainly used and some of the experimental data measured by D.Heijboer (May 1988 TU Delft) are selected as comparisons. For convenience this report is divided in two parts. Part I contains all texts and illustrative figures, Part 11 contains all figures of calculation results. (All computer programs, their input data and outputs for this study are available in the Delft University of Technology).Hydraulic EngineeringCivil Engineering and Geoscience