Gravity Currents in a Vegetated Valley of Trapezoidal Shape

سال انتشار: 1395
نوع سند: مقاله ژورنالی
زبان: انگلیسی
مشاهده: 100

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شناسه ملی سند علمی:

JR_JAFM-9-3_003

تاریخ نمایه سازی: 3 بهمن 1400

چکیده مقاله:

In this study lock-exchange experiments are performed in a tank of rectangular upper cross section and a lower vegetated valley of trapezoidal shape to study the effect of drag resistance, due to vegetation, on gravity currents. Many natural and man-made channels are approximately trapezoidal. For the simulation of the vegetation the bed is covered by flexible grass vegetation (height of vegetation, hv=۲.۰cm) of different submergence ratio hν/H (hν=height of vegetation, H=water depth). The motion of the gravity current is monitored with a digital video of high definition, the front velocity is measured and the height of the front is captured. Twenty four experiments are performed, twelve inside the trapezoidal section (H/Htr=۰.۴, ۰.۶ or ۰.۸) and twelve over the trapezoidal section (H/Htr=۱.۲, ۱.۴ or ۱.۶). The initial Reynolds number, based on the height of the valley and the reduced gravity, is greater than ۱۰۰۰۰ for all cases indicating that the gravity currents are turbulent. Results are compared with those of similar experiments without vegetation (Keramaris and Prinos, ۲۰۱۰) and hence the effect of the vegetation drag resistance on the motion of the current is investigated. The main conclusion of this study is that the shape of the tank plays a significant role in the propagation of gravity currents. The presence of trapezoidal increases the velocity of gravity currents in comparison with triangular or orthogonal shape.

نویسندگان

E. Keramaris

University of Thessaly, Department of Civil Engineering, Division of Hydraulic and Environmental Engineering, Volos, Greece

P. Prinos

Aristotle University of Thessaloniki, Department of Civil Engineering, Thessaloniki, Greece