Abstract
Riparian and floodplain tree-like emergent vegetation alter significantly the flow field and lead to complicated three-dimensional flow patterns, characterized by increased turbulence production, with the potential to induce morphological changes. The canopy presence in tree-like vegetation leads to the formation of lee wake vortices and can induce a strong subcanopy flow. The present experimental study employs artificial, rigid, tree-like emergent vegetation elements, with relatively simple structure, in order to investigate the canopy effects on the flow field. Specifically, the tree-like canopy is simulated by placing an element on top of a wooden rod simulating the trunk. Three elements with an equal encircling diameter of 16 cm are examined as canopy in tree-like vegetation, namely a circular cylinder and two hexagonal arrays comprising smaller circular cylinders with two different individual diameters. The experiments were conducted in a 26 m long laboratory flume and the velocity measurements were carried out with an acoustic Doppler velocimeter. The results show that the canopy porosity has a direct impact on the subcanopy flow intensity and on the required distance that the flow needs to recover. In addition, the subcanopy flow disrupts the formation of a steady wake region behind the entire porous element and inhibits the development of a recognizable von Karman vortex street.
Original language | English |
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Pages (from-to) | 1283-1308 |
Number of pages | 26 |
Journal | Environmental Fluid Mechanics |
Volume | 16 |
Issue number | 6 |
DOIs | |
Publication status | Published - 1 Dec 2016 |
Bibliographical note
Publisher Copyright:© 2016, Springer Science+Business Media Dordrecht.
Funding
Vasileios Kitsikoudis gratefully acknowledges the financial support for conducting post-doctoral research in Istanbul Technical University, initially from Anastasios Anastasiadis foundation (grant number 63310/25-09-2013) and afterwards from the Scientific and Technological Research Council of Turkey (TUBITAK)—Fellowship Program 2216 (Ref. No. 21514107-115.02-45898). The authors would like to thank the Editor in Chief for handling the manuscript and two anonymous Reviewers, whose insightful comments and constructive suggestions improved the technical content and presentation of the paper. Finally, thanks go to ITU Hydraulics Laboratory technicians Mevlut Ulucinar, Hasan Yalcin, and Yasar Aktas.
Funders | Funder number |
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Anastasios Anastasiadis foundation | 63310/25-09-2013 |
TUBITAK | 21514107-115.02-45898 |
Türkiye Bilimsel ve Teknolojik Araştirma Kurumu | |
Istanbul Teknik Üniversitesi |
Keywords
- Emergent vegetation
- Experimental hydraulics
- Flow-vegetation interaction
- Open channel hydraulics
- Subcanopy flow
- Tree-like vegetation