Premium
The influence of migrating bed forms on the velocity‐intermittency structure of turbulent flow over a gravel bed
Author(s) -
Keylock Christopher J.,
Singh Arvind,
FoufoulaGeorgiou Efi
Publication year - 2013
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/grl.50337
Subject(s) - intermittency , turbulence , mechanics , reynolds number , flow (mathematics) , scaling , physics , geology , reynolds averaged navier–stokes equations , laminar flow , statistical physics , classical mechanics , geometry , mathematics
Modeling turbulent flows at high Reynolds number requires solving simplified variants of the Navier‐Stokes equations. The methods used to close the resulting Reynolds‐averaged, or eddy simulation equations usually follow classical theory and, at small enough scales, postulate universal scaling for turbulence that is independent of the velocity itself. This may not be the best way to conceptualize geophysical turbulence. Turbulent intermittency may be defined in terms of the local “roughness” of the velocity signal as measured by pointwise Hölder exponents. This study investigates the joint velocity‐intermittency structure of flow over a gravel‐bed surface with migrating bed forms. We report clear velocity‐intermittency dependence and quantify its nature above the moving bed form profile. Our results imply differences in energy transfer close to bed forms at shorter wavelengths than those forced directly. Hence, progress in modeling flows of geophysical relevance may require a reconsideration of the principles on which turbulence closures are based.