Abstract
Biofilms attached on permeable structures in coastal areas can purify the water.It's efficiency is dependent on mass transfer in permeable structures.Mass transfer mechanism in a permeable breakwater was studied in an experimental channel which have a permeable breakwater composed of 7.5cm-diameterstyrene-balls.
Velocity fluctuation in the permeable breakwater was measured by a Laser Doppler Velocimeter and was found to have both wave components and turbulent components. Dispersion coefficient in the breakwater was measured using a chloride-tracer method and was divided into dispersion component and diffusion component. The dispersion coefficient was expressed as the product of root-mean-square-velocity of the wave motion and the void scale while the diffusion coefficient was expressedas the product of turbulence and the void scale.
