Grain size influence on sediment transport in sheet flow conditions for combined wave-current flow

Grain size influence on sediment transport in sheet flow conditions for combined wave-current flow

Van der Wal, R.J.

D' Angremond, K. (mentor)

Civil Engineering and Geosciences

Hydraulic Engineering

1996-11-01

Especially during storms the coast-profile can change dramatically. During storms large waves cause high oscillatory water velocities near the bottom and the bed becomes plane and sheet flow becomes the dominant sediment transport mode. Because field measurements are difficult to perform in-situ, laboratory experiments concerning these processes are a good alternative. Because of the complex physics of the problem it is not possible to make a suitable scale model. Therefore full scale models are applied, although these facilities are very expensive and hence scarce. Full scale models are built in the form of oscillating water tunnels. The present sediment transport experiments were performed in the Large Oscillating Water Tunnel (LOWT) of DELFT HYDRAULICS. The main scope of this study is to obtain data for the verification and development of sediment transport models and to investigate the influence of the grain diameter on the net sediment transport. All experiments concern combined waves and current in sheet flow (plane bed) conditions, using sand with a small grain size: 0.13 mm. The wave period varied from 4 s to 12 s. The major part of the experiments concerned a wave period of 7.2 s. The conditions (10) were chosen such that they all lie within the sheet flow regime and such that 2 conditions correspond to previous experiments with a different grain diameter. Different combinations of a mean current and oscillatory wave velocity were chosen. Also the influence of the wave period is checked by varying the wave period. The number of tests performed for this study amounted 60 and were performed in the period October 1995-January 1996. The experiments were performed in the framework of the project KUST*2000 of Rijkswaterstaat (RIKZ). The results of the present study are also used in the STW project which is carried out by Delft University of Technology (STW: Stichting voor de Technische Wetenschappen/Technology Foundation). The analysis of the raw data was conducted by the different members of the research team. A complete overview of the processed data can be found in the data report .

oscillating water tunnel
sediment transport
waves
bed shear stress

http://resolver.tudelft.nl/uuid:010ff79f-447c-4dda-8ab0-3bed4eb57baa

Student theses

master thesis

(c) 1996 Van der Wal, R.J.