TY - JOUR
T1 - Hydraulic resistance in open-channel flows over self-affine rough beds
AU - Stewart, Mark T.
AU - Cameron, Stuart M.
AU - Nikora, Vladimir I.
AU - Zampiron, Andrea
AU - Marusic, Ivan
N1 - Acknowledgements
The authors wish to express their gratitude to Stephan Spiller for advice regarding the silicone moulds, to Cameron Scott for assisting with manufacturing of the roughness elements and Davide Collautti for help with conducting experiments.
PY - 2019
Y1 - 2019
N2 - Knowledge of hydraulic resistance of single-valued self-affine fractal surfaces remains very limited. To advance this area, a set of experiments have been conducted in two separate open-channel flumes to investigate the effects of the spectral structure of bed roughness on the drag at the bed. Three self-affine fractal roughness patterns, based on a simple but realistic three-range spectral model, have been investigated with spectral scaling exponents of −1, −5/3 and −3, respectively. The different widths of the flumes and a range of flow depths also afforded an opportunity to consider effects of the flow aspect ratio and relative submergence. The results show that with all else equal the friction factor increases as the spectral exponent decreases. In addition, the relationship between the spectral exponent and effective slope of the roughness is demonstrated, for the first time. Aspect ratio effects on the friction factor within the studied range were found to be negligible.
AB - Knowledge of hydraulic resistance of single-valued self-affine fractal surfaces remains very limited. To advance this area, a set of experiments have been conducted in two separate open-channel flumes to investigate the effects of the spectral structure of bed roughness on the drag at the bed. Three self-affine fractal roughness patterns, based on a simple but realistic three-range spectral model, have been investigated with spectral scaling exponents of −1, −5/3 and −3, respectively. The different widths of the flumes and a range of flow depths also afforded an opportunity to consider effects of the flow aspect ratio and relative submergence. The results show that with all else equal the friction factor increases as the spectral exponent decreases. In addition, the relationship between the spectral exponent and effective slope of the roughness is demonstrated, for the first time. Aspect ratio effects on the friction factor within the studied range were found to be negligible.
KW - Bed roughness
KW - Drag coefficient
KW - Hydraulic resistance
KW - Open channel flow turbulence
KW - self affine fractal surface
KW - hydraulic resistance
KW - drag coefficient
KW - open-channel flow turbulence
KW - self-affine fractal surface
KW - TURBULENT-FLOW
KW - SIMULATION
UR - http://www.scopus.com/inward/record.url?scp=85049604737&partnerID=8YFLogxK
UR - http://www.mendeley.com/research/hydraulic-resistance-openchannel-flows-selfaffine-rough-beds
UR - https://abdn.pure.elsevier.com/en/en/researchoutput/hydraulic-resistance-in-openchannel-flows-over-selfaffine-rough-beds(9ba75950-9bc8-4d98-8812-33515475c90b).html
U2 - 10.1080/00221686.2018.1473296
DO - 10.1080/00221686.2018.1473296
M3 - Article
VL - 57
SP - 183
EP - 169
JO - Journal of Hydraulic Research
JF - Journal of Hydraulic Research
SN - 0022-1686
IS - 2
ER -
