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Lock-Exchange Experiments: Effect of Vegetation Drag on Gravity Currents

Author(s): Keramaris Evangelos; Prinos Panayotis

Linked Author(s): Panagiotis Prinos

Keywords: Gravity currents; Vegetation Density; Lock-Exchange; DragResistance

Abstract: In this work lock-exchange experiments were carried out in a 2D flume to study the effect of drag resistance, due to vegetation, on gravity currents. For the simulation of the vegetation the bed is covered by rods bundle with height hv eg=11cm. Both submerged and emergent vegetation was investigated with the ratio H/hv eg (H is the water depth) ranging from 0.63 to 1.0 (submerged case) and from 1.27 up to 2.18 (emergent case). Density difference between salt water and clear water was varied between 0.1 % and 0.3 % (ρw=1000 kg/m`3, ρsw=1010 or 1020 or 1030 kg/m`3). The effect of vegetation density on the motion of the gravity current was also investigated by varying the number of the rods from (a) 1440rods/m`2to (b) 2850rods/m`2. The experimental set-up is shown in figure 1. The movement of the gravity current was monitored with digital video of high definition, the front velocity was measured and the height of the front was captured. Results are compared satisfactorily with similar experiments performed by Tanino et al. (2005). They are compared also with experimental data of Shin et al. (2004) for gravity currents over a bed without vegetation.


Year: 2009

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