EFFECTS OF PARTICLE SIZE AND WAVE STATE ON GRAIN DISPERSION.
CHICAGO UNIV ILL FLUID DYNAMICS AND SEDIMENT TRANSPORT LAB
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The dispersion of three sizes of tagged grains normal to the shoreline by shoaling wind waves was studied in Buzzards Bay, Massachusetts. Experiments were restricted to periods during which wave crests approached parallel to the shoreline. Determination of the frequency of tagged grains in samples taken from the bottom lead to the construction of concentration maps. Analysis of the concentration maps yielded a value of an index of net movement for each grain size in each experiment. The maximum horizontal velocity under the wave crest near the bottom was computed from measurements of wave geometry and water depth. Within the experimental range of the data it is concluded that under the same wave conditions, finer grain sizes have a greater tendency to move offshore than coarser grains. A change in wave state resulting in an increase in the maximum horizontal velocity near the bottom produces an increase in the tendency for all test grain sizes to move seaward. Theoretical concentrations computed from the equations of turbulent diffusion of contaminant particles in the atmosphere agree qualitatively with the empirical observations of this study and help to explain them. Author
- Physical and Dynamic Oceanography
- Geology, Geochemistry and Mineralogy
- Civil Engineering