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Direct estimates of friction factors for a mobile rippled bed
Author(s) -
RodríguezAbudo S.,
Foster D. L.
Publication year - 2017
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/2016jc012055
Subject(s) - momentum (technical analysis) , mechanics , turbulence , ripple , dissipation , quadratic equation , shear stress , turbulence kinetic energy , physics , momentum transfer , flux (metallurgy) , geotechnical engineering , classical mechanics , mathematics , geology , materials science , geometry , optics , thermodynamics , power (physics) , finance , metallurgy , scattering , economics
New friction factor estimates are computed from the total momentum transfer applied to a rippled sediment bed. The total time‐dependent momentum flux is achieved by implementing the double‐averaged horizontal momentum equation on the nearbed flow field collected with PIV. Time‐independent friction factors are obtained by regressing the total momentum flux to the common quadratic stress law given by1 2 ρ u ∞ | u ∞ | . The resulting friction factors compare favorably with available analysis techniques including energy dissipation, vertical turbulence intensity, and maximum shear stress, but can be 2‐6 times smaller than estimates determined with the model by Madsen (1994) and the formula of Swart (1974) using the ripple roughness.