Turbulence characteristics of favorable pressure gradient flows in gravel-bed channel with vegetated walls

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Title:Turbulence characteristics of favorable pressure gradient flows in gravel-bed channel with vegetated walls
Creators:
Najafabadi, Elham Fazel; Department of Water Engineering, Isfahan University of Technology, Isfahan, 84156‐83111, Iran.
Afzalimehr, Hossein; Department of Water Engineering, Isfahan University of Technology, Isfahan, 84156‐83111, Iran.
Sui, Jueyi; jueyi dot sui at unbc dot ca; Environmental Engineering Program, University of Northern British Columbia, 3333 University Way, Prince George, BC, Canada.
Journal or Publication Title:
Journal of Hydrology and Hydromechanics, 63, 2, pp. 154-163
Uncontrolled Keywords:favorable pressure gradient flow, vegetation, gravel, quadrant analysis, stress fraction, Reynolds stress

Abstract

Field observations showed that in many gravel-bed rivers, rice stems and gravel interact with each other and affect the flow structure. This calls to conduct research in more details in laboratory to better understand impacts of interaction between rice stems and gravel bed rivers on the flow structure. The outcome of such investigations can improve the estimation of drag coefficient in hydrodynamic models. Experiments were carried out in a flume with gravel bed and the vegetated vertical flume walls to investigate turbulence characteristics under favorable pressure gradient flows. Results showed that the stress fraction involves both the sweep and ejection dominance near the vegetated flume walls, showing no negative Reynolds shear stress near water surface. The values of exuberance ratio play a significant role on the magnitude of the Reynolds shear stress which varies with the distance from the vegetation. Quadrant analysis reveals that a major part of the momentum flux is transported during a short period of strong turbulence activity near the bed at the central axis. Augmentation of the hole size makes difference between contributions of sweep and ejection with those of the outward and inward interactions near the bed, however, the hole size doesn’t play any role near the water surface.

Official URL: http://147.213.145.2/vc/vc1.asp

Title:Turbulence characteristics of favorable pressure gradient flows in gravel-bed channel with vegetated walls
Translated title:Turbulence characteristics of favorable pressure gradient flows in gravel-bed channel with vegetated walls
Creators:
Najafabadi, Elham Fazel; Department of Water Engineering, Isfahan University of Technology, Isfahan, 84156‐83111, Iran.
Afzalimehr, Hossein; Department of Water Engineering, Isfahan University of Technology, Isfahan, 84156‐83111, Iran.
Sui, Jueyi; jueyi dot sui at unbc dot ca; Environmental Engineering Program, University of Northern British Columbia, 3333 University Way, Prince George, BC, Canada.
Uncontrolled Keywords:favorable pressure gradient flow, vegetation, gravel, quadrant analysis, stress fraction, Reynolds stress
Subjects:T Technology > TA Engineering (General). Civil engineering (General)
Divisions:Mathematics, Physics and Earth Sciences > Institute of Hydrodynamics > Journal of Hydrology and Hydromechanics
Journal or Publication Title:Journal of Hydrology and Hydromechanics
Volume:63
Number:2
Page Range:pp. 154-163
ISSN:0042-790X
Publisher:Institute of Hydrology of the Slovak Academy of Sciences and the Institute of Hydrodynamics of the Academy of Sciences of the Czech Republic
Related URLs:
URLURL Type
http://avi.lib.cas.cz/node/55Publisher
ID Code:8395
Item Type:Article
Deposited On:07 Apr 2015 13:04
Last Modified:07 Apr 2015 11:04

Citation

Najafabadi, Elham Fazel; Afzalimehr, Hossein; Sui, Jueyi (2015) Turbulence characteristics of favorable pressure gradient flows in gravel-bed channel with vegetated walls. Journal of Hydrology and Hydromechanics, 63 (2). pp. 154-163. ISSN 0042-790X

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