Hydraulic radius for evaluating resistance induced by simulated emergent vegetation in open-channel flows
Nguyen, Hoai Thanh
Date of Issue2011
School of Civil and Environmental Engineering
The resistance induced by simulated emergent vegetation in open-channel flows has been interpreted differently in the literature, largely attributable to inconsistent uses of velocity and length scales in the definition of friction factor or drag coefficient and Reynolds number. By drawing analogies between pipe flows and vegetated channel flows, this study proposes a new friction function with the Reynolds number that is redefined by using a vegetation-related hydraulic radius. The new relationship is useful for consolidating various experimental data across a wide range of vegetation density. The results clearly show a monotonic decrease of the drag coefficient with the new Reynolds number, which is qualitatively comparable to other drag coefficient relationships for nonvegetated flows. This study also proposes a procedure for correcting sidewall and bed effects in the evaluation of vegetation drag.
DRNTU::Engineering::Civil engineering::Water resources
Journal of hydraulic engineering
© 2011 ASCE. This is the author created version of a work that has been peer reviewed and accepted for publication by Journal of Hydraulic Engineering, American Society of Civil Engineers. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at: [DOI: http://dx.doi.org/10.1061/(ASCE)HY.1943-7900.0000377].