Affiliation: | (1) Graduate School of Bioresource and Bioenvironmental Sciences, Kyusyu Univ., Hakozaki 6–10–1, Higashi-ku, 812–8581 Fukuoka, Japan;(2) Faculty of Agriculture, Kyushu Univ., Hakozaki 6–10–1, Higashi-ku, 812–8581 Fukuoka, Japan |
Abstract: | It has recently been proposed that water purification could be performed using aquatic plants, since they absorb nutrient salts. The behavior of a substance in a closed water area is affected by turbulent flows from wind-induced flow, which is a mechanical disturbance, and convective flow, which is a thermal disturbance. In a closed density stratified water area, wind-induced flow gives rise to the entrainment phenomenon at the density interface. This phenomenon, which is based on mixing between the upper and lower water layers, lowers the density interface and so affects the water quality. We experimentally investigated the effect of aquatic plants on the turbulent flow from a mechanical disturbance in the closed water area. Results indicated that the presence of floating and submerged plants had a significant effect on the scale of the turbulent entrainment, and that the entrainment velocity depended on the overall Richardson number to the power of –3/2. |