Experimental investigation of channel flow through idealized isolated tree-like vegetation


Kitsikoudis V., Yağcı O., Kırca V. Ş. Ö. , KELLECIOGLU D.

ENVIRONMENTAL FLUID MECHANICS, vol.16, no.6, pp.1283-1308, 2016 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 16 Issue: 6
  • Publication Date: 2016
  • Doi Number: 10.1007/s10652-016-9487-7
  • Journal Name: ENVIRONMENTAL FLUID MECHANICS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.1283-1308
  • Keywords: Emergent vegetation, Experimental hydraulics, Flow-vegetation interaction, Open channel hydraulics, Subcanopy flow, Tree-like vegetation, DOPPLER-VELOCIMETER DATA, UNCOMPACTED CROWN RATIO, TURBULENCE STRUCTURE, RIPARIAN VEGETATION, CIRCULAR ARRAY, RIVER, EQUATIONS, PATTERNS, HYDRODYNAMICS, VELOCITY
  • Istanbul Technical University Affiliated: Yes

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.