Rough-bed flows in geophysical, environmental, and engineering systems : Double-Averaging Approach and its applications. Preface to the Special Issue

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Momentum and energy transfer in open-channel flow over streamwise ridges

Acknowledgements. Discussions with I. Marusic (University of Melbourne) and B. Ganapathisubramani (University of Southampton) are greatly appreciated. Funding. Financial support was provided by the EPSRC/UK grant ‘Bed friction in rough-bed free-surface flows: a theoretical framework, roughness regimes, and quantification’ (grant EP/K041088/1). Open access via Cambridge press agreementPeer reviewedPublisher PD

Entrainment of sediment particles by very-large-scale motions

Acknowledgements The study has been supported by two EPSRC/UK grants, ‘High-resolution numerical and experimental studies of turbulence-induced sediment erosion and near-bed transport’ (EP/G056404/1) and ‘Bed friction in rough-bed free-surface flows: a theoretical framework, roughness regimes, and quantification’ (EP/K041088/1). The authors are grateful to three anonymous reviewers and the Editor for constructive criticisms and helpful suggestions that improved the presentation of the material in the paper.Peer reviewedPostprin

Interactions between aquatic plants and turbulent flow : A field study using stereoscopic PIV

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Flow interactions with an aquatic macrophyte: a field study using stereoscopic particle image velocimetry

This paper reports the morphology of a natural patch of Ranunculus penicillatus and presents high-resolution measurements of flow velocities in its wake using a stereoscopic PIV field measurement system. The patch was 3.80 m long, 1.24 m wide and caused substantial changes to downstream mean velocities and turbulence. Vertical profiles of streamwise mean velocity were not logarithmic and flow was redirected under the positively buoyant canopy, enhancing vertical turbulent mixing in the wake and generating a large region where the velocity covariance u'w' was positive. Turbulent kinetic energy was enhanced downstream from the patch lateral shear layer, but not at the centre of the wake. Spectra downstream from the patch showed that turbulence was neither dominated by fine-scale nor large-scale structures, likely due to the low energy of the flow conditions and lack of a developed vortex street within the measurement domain. Sedimentation was observed at the upstream end of the patch, but not underneath the floating canopy. The methods and results of this work will be useful for planning other in situ studies. Also, the reported data on macrophyte geometry and biometrics will assist with the design of more realistic replicas for use in laboratory studies

High-resolution measurements of swordfish skin roughness

Acknowledgments M S acknowledges financial support from the NERC Discipline Hopping for Environmental Solutions fund. V N, S C, M S, and A Z have been partly supported by EPSRC Grants ‘Bed friction in rough-bed freesurface flows: a theoretical framework, roughness regimes, and quantification’ (EP/K041088/1) and ‘Secondary currents in turbulent flows over rough walls’ (EP/V002414/1).Peer reviewedPublisher PD