標題: The role of rooted emergent vegetation on periodically thermal-driven flow over a sloping bottom
作者: Lin, Ying-Tien
Wu, Chin H.
環境工程研究所
Institute of Environmental Engineering
關鍵字: Thermal-driven flow;Sloping bottom;Rooted emergent vegetation;Diurnal heating and cooling
公開日期: 1-十二月-2014
摘要: Thermal-driven flow is generated due to topographic or vegetation-shading effects. Asymptotic solutions by assuming a small bottom slope are derived to discuss effects of rooted emergent vegetation and interactions between emergent vegetation and sloping topography on thermal-driven flow during diurnal heating and cooling cycles. The results show that the zero-order horizontal velocity is significantly reduced by vegetative drag, and the time lag between the change of horizontal velocity and the reversal of pressure gradient is also shortened. The solutions reveal that the viscous effect is dominant in very shallow water, and the drag force becomes important as the water depth increases. The inertial term is only important at the very beginning stage of flow initiation. Different vegetation distributions can significantly change the temperature fields that then affect patterns of thermal-driven circulation and exchange flowrates. For the case of tall vegetation growth in shallow water, and when the deep water side is open, the effects of vegetation shading may interfere with the topographic effects and dramatically alter the flow patterns. The blockage of solar radiation due to vegetation shading can determine the patterns and magnitude of thermal-driven flow. By means of the derived asymptotic horizontal velocity, exchange flow rates can be estimated, which are in good agreement with previous studies. The limitation and valid ranges of asymptotic solutions are finally discussed.
URI: http://dx.doi.org/10.1007/s10652-014-9336-5
http://hdl.handle.net/11536/124100
ISSN: 1567-7419
DOI: 10.1007/s10652-014-9336-5
期刊: ENVIRONMENTAL FLUID MECHANICS
Volume: 14
起始頁: 1303
結束頁: 1334
顯示於類別:期刊論文


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