Abstract
In the last few decades extensive studies focusing on both qualitative and quantitative descriptions of the Reynolds stress within aquatic canopies have been carried out. Although these studies have advanced our knowledge of mechanics of flow-vegetation interactions, further research in this area is still required. In particular, there is a need for development of new simple physically-based relationships describing the Reynolds stress profiles within submerged vegetation canopies. This paper addresses this issue and proposes a physically justified formulation for the Reynolds stress profile within the canopy region.
Highlights
Many phenomena in open-channel flows such as flow resistance, transport of pollutants, deposition and erosion of sediments are directly influenced by the primary Reynolds stress
Within the upper canopy the momentum transport is dominated by the total vertical momentum flux, while in the lower canopy part it is dominated by the gravity action
The ratio of the drag forces acting in the upper and lower canopy regions is approximated by a simple non-linear relationship that links this ratio to the relative penetration depth hτ / /hc and flow submergence H / hc
Summary
Many phenomena in open-channel flows such as flow resistance, transport of pollutants, deposition and erosion of sediments are directly influenced by the primary Reynolds stress. Within the LC region, the flow is mainly controlled by the balance of the gravity and total drag forces, while the total vertical momentum flux being negligible (Fig. 1) In this canopy region, the flow velocity and drag coefficient profiles are approximately constant. Assuming that the drag force within the canopy is approximately constant after integration of Eq (1) we obtain a linear relationship for the total fluid stress within the UC region:. Using the DANS momentum equation for steady and uniform 2D open-channel flow within the vegetation canopy, a simple relationship (4) for the total fluid stress and an expression for the drag force ratio (7) are deduced. The details on the experimental data and their analysis are presented
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