Reynolds number variation in oscillatory boundary layers: Part I. Purely oscillatory motion |
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| Institution: | 1. Department of Physical Chemistry, Faculty of Sciences, University of Vigo, Ourense, Spain;2. Chemistry Department, REQUIMTE-CQFB, Faculty of Science and Technology, New University of Lisbon, Caparica, Portugal;1. College of Harbour, Coastal and Offshore Engineering, Hohai University, Nanjing, China;2. Deltares, Delft, The Netherlands;3. Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft, The Netherlands;4. MOE Key Laboratory for Coast and Island Development, Nanjing University, Nanjing, China;5. Nanjing Hydraulic Research Institute, Nanjing, China;6. State Key Laboratory for Estuarine and Coastal Studies, East China Normal University, Shanghai, China |
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| Abstract: | A numerical model based upon a low Reynolds number turbulence closure is proposed to study Reynolds number variation in reciprocating oscillatory boundary layers. The model is used to compute the boundary layer for flow regimes ranging from smooth laminar to rough turbulent. Criteria for fully developed turbulence are derived for walls of the smooth and rough types. In particular, a new criterion to identify the rough turbulent regime is determined based on the time-averaged turbulence intensity. The reliability of the present model is assessed through comparisons with detailed experimental data collected by other investigators. The model globally improves upon standard high Reynolds number closures. Variation through the wave cycle of the main flow variables (ensemble-averaged velocity, shear stress, turbulent kinetic energy) is remarkably well-predicted for smooth walls. Predictions are satisfactory for rough walls as well. Yet, the turbulence level in the rough turbulent regime is overpredicted in the vicinity of the bed. |
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