Author(s): Nina Nikora

Linked Author(s): Nina Nikora

Keywords: Vegetated flow, Reynolds stress, drag, open-channel flow

Abstract: Vertical profile of the primary Reynolds stress within a submerged vegetation canopy reflects complex mechanics of flow-vegetation interactions. Over 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. According to this formulation, the vegetation layer is subdivided into the upper and lower canopy regions with distinctly different momentum transport and drag-forming mechanisms. The key parameters of the proposed relationship are the penetration depth (i. e. , the distance from the bed to a point where the downward turbulent flux becomes negligible) and the ratio of drag forces acting in the upper and lower canopy regions. The relationship was tested using extensive laboratory experiments that show that the relationship parameters are affected by both bulk flow conditions and vegetation characteristics

DOI:

Year: 2017