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Low relative-submergence effects in a rough-bed open-channel flow

Rouzès, Maxime and Moulin, Frédéric Y. and Florens, Emma and Eiff, Olivier Low relative-submergence effects in a rough-bed open-channel flow. (2018) Journal of Hydraulic Research, 56. 1-28. ISSN 0022-1686

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Official URL: https://doi.org/10.1080/00221686.2018.1478894


Multi-plane stereoscopic PIV measurements were performed in an open-channel flume fitted with cubes to investigate very low submergence ratios, h/k = {1.5, 2, 3}, where h is the water depth and k the roughness height. The spatial standard deviation of the mean flow components reveals that the extent of the roughness sublayer increases drastically with the decrease in h/k to span the entire water column for the lowest h/k investigated. Despite this, the logarithmic law is still observed on the double-averaged velocity profiles for all h/k, first with a fixed von Kármán constant κ and, second, via the indicator function where κ is a free parameter. Also, the longitudinal and vertical normal stresses indicate a universal boundary layer behaviour independent of h/k. The results suggest that the logarithmic and wake-defect laws can still be applied at such low h/k. However, the lateral normal stress depends on h/k in the range investigated as well as on the geometry of the roughness pattern.

Item Type:Article
HAL Id:hal-02135758
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
Other partners > Karlsruhe Institute of Technology - KIT (GERMANY)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
Laboratory name:
Research infrastructures Hydralab - Agence National de la Recherche (ANR)
Deposited On:20 Mar 2019 07:52

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