Wind-Induced Phenomenon in a Closed Water Area with Floating-Leaved Plant

Authors: Akinori Ozaki

Abstract:

In this study, in order to clarify wind-induced phenomena, especially vertical mixing of density stratification in a closed water area with floating-leaved plants, we conducted hydraulic experiments on wind flow characteristics, wind wave characteristics, entrainment phenomena and turbulent structure by using a wind tunnel test tank and simulated floating-leaved plants. From the experimental results of wind flow and wind wave characteristics, we quantified the impact of the occupancy rate of the plants on their resistance characteristics. From the experimental results of entrainment phenomena, we defined the parameter that could explain the magnitude of mixing between the density stratifications, and quantified the impact of the occupancy rate on vertical mixing between stratifications. From the experimental results of the turbulent structure of the upper layer, we clarified the differences in small-scale turbulence components at each occupancy rate and quantified the impact of the occupancy rate on the turbulence characteristics. For a summary of this study, we theoretically quantified wind-induced entrainment phenomena in a closed water area with luxuriant growth of floating-leaved plants. The results indicated that the impact of luxuriant growth of floating-leaved plants in a closed water body could be seen in the difference in small-scale fluid characteristics, and these characteristics could be expressed using the small-scale turbulent components.

Keywords: Density Stratification, Floating-leaved Plant, Wind-induced Entrainment Phenomenon, Turbulent Structure

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1055613

References:

[1] Mori, K., Tohara, Y. and Kato O "Experimental Research of Entrainment Rate of Density Interface due to a Wind Induced Current" Transaction of the Japanese society of irrigation, drainage and reclamation engineering. 1989, Vol. 144, pp.85-93
[2] Wu, J. "Wind-Induced Turbulent Entrainment Across a Stable Density Interface", Journal of Fluid Mechanics, 1973, 61, pp. 275-287.
[3] Kit,E., Berent,E. and Vajda,M. "Vertical Mixing Induced by Wind and a Rotating Screen in a Stratified Fluid in a Channel", Journal of Hydraulic Research. 1980, 18, pp.35-58
[4] Ikushima, K. "Substance Production of Plant Community near Water", Kyoritsu Publishing, Tokyo, 1974
[5] Shemdin,O.H. "Wind-Generated Current and Phase Speed of Wind Waves". Journal of Physical Ocean, 1972, 2, pp.411-419
[6] Wu, J. "Wind-Induced Drift Currents". Journal of Fluid Mechanics, 1975, 68,pp.49-70
[7] Tsuruya, H. "Experimental Study of Wind Driven Currents in a Wind-Wave Tank -Effect of Return Flow on Wind Driven Currents-", Report of the Port and Harbor Research Institute, 1983, Vol.22, No.2, pp.128-174
[8] Kraus, E.B. and Turner, J.S. "A One-Dimensional Model of the Seasonal Thermocline The general theory and its consequences", Tellus, 1967, 19, pp. 98-106
[9] Nakayama, T. and Nezu, I. "Turbulence Structure of Wind Water Waves", Journal of Japan Society of Civil Engineering, 2000, No.642,Ôàí-50, pp. 45-56
[10] Takahashi, A. and Suga, A. "Entrainment Coefficient in the Salt-Water Fresh-Water Stratification", Proceedings of Annual Conference of the Japan Society of Civil Engineers, 1976, No.2, pp383-384
[11] Ura, M. "Variation of Density Interface and Entrainment Velocity Induced by Wind Shear", Proceedings of Coastal Engineering. JSCE. 1983, Vol.30, pp.561-565