AbstractIn the present work, an investigation on the hydrodynamics of wave-current orthogonal combined flow has been carried out. The work focuses on the effects of the oscillatory flow superposed on the current steady boundary layer, and on how the oscillatory flow affects the current velocity distribution. A laboratory experimental campaign of wave-current orthogonal interaction has been carried out in a shallow water basin at DHI Water and Environment (Horsholm, Denmark), in order to investigate the orthogonal combined flow in the presence of different roughness beds. Mean flow has been investigated by computing time- and space-averaged velocity profiles. Friction velocity and equivalent roughness have been inferred from the velocity profiles by best fit technique, in order to quantify the shear stress experienced by the current mean flow. Tests in the presence of only current, only waves and combined flow have been performed. Instantaneous velocities have been Reynolds-averaged in order to obtain turbulent fluctuations time series and compute turbulence related quantities, such as Reynolds stresses. The mean current velocity profiles have been also compared with a selection of analytical models in order to assess their validity for the case of wave-current orthogonal flow for the considered wave and current condition ranges. The analysis of the mean flow revealed a complex interaction of the waves and currents combined flow. Depending on the relative strength of the current with respect to the waves, the superposition of the oscillatory flow may determine an increase or a decrease of the bottom friction experienced by the current. Such a behavior is also strictly related to the bed physical roughness. Analysis of the turbulence Reynolds stresses seems to confirm the results of the mean flow investigation.
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K. H. Andersen and C. Faraci. The wave plus current flow over vortex ripples at an arbitrary angle. Coastal engineering, 47(4):431–441, 2003.
M. Arnskov, J. Fredsøe, and B. Sumer. Bed shear stress measurements over a smooth bed in three dimensional wave-current motion. Coastal Engineering, 20(3-4):277–316, 1993.
W. Bakker. Sand concentration in an oscillatory flow. In Coastal Engineering 1974, pages 1129–1148. 1975.
W. T. Bakker and T. Van Doorn. Near-bottom velocities in waves with a current. In Coastal Engineering 1978, pages 1394–1413. 1978.
E.W. Bijker. The increase of bed shear in a current due to wave action. In Coastal Engineering 1966, pages 746–765. 1967.
J. B. Christoffersen and I. G. Jonsson. Bed friction and dissipation in a combined current and wave motion. Ocean Engineering, 12(5):387–423, 1985.
P. C. Fernando, J. Guo, and P. Lin. Wave–current interaction at an angle 1: experiment. Journal of hydraulic research, 49(4):424–436, 2011.
J. Fredsøe. Turbulent boundary layer in wave-current motion. Journal of Hydraulic Engineering, 110(8): 1103–1120, 1984.
W. D. Grant and O. S. Madsen. Combined wave and current interaction with a rough bottom. Journal of Geophysical Research: Oceans, 84(C4):1797–1808, 1979.
W. D. Grant and O. S. Madsen. The continental-shelf bottom boundary layer. Annual review of fluid mechanics, 18(1):265–305, 1986.
F. Havinga. Sediment concentrations and sediment transport in case of irregular non-breaking waves with a current. 1992.
P. Kemp and R. Simons. The interaction between waves and a turbulent current: waves propagating with the current. Journal of Fluid Mechanics, 116:227–250, 1982.
P. Kemp and R. Simons. The interaction of waves and a turbulent current-waves propagating against the current. J Fluid Mech, 130(MAY):73–89, 1983.
K. Y. Lim and O. S. Madsen. An experimental study on near-orthogonal wave–current interaction over smooth and uniform fixed roughness beds. Coastal Engineering, 116:258–274, 2016.
C. Lodahl, B. M. Sumer, and J. Fredsøe. Turbulent combined oscillatory flow and current in a pipe. Journal of Fluid Mechanics, 373:313–348, 1998.
M. Marino, C. Faraci, and R. E. Musumeci. An experimental setup for combined wave-current flow interacting at a right angle over a plane beach. Italian Journal of Engineering Geology and Environment, 1: 99–106, 2020a.
M. Marino, C. Faraci, and R. E. Musumeci. Shoaling waves interacting with an orthogonal current. Journal of Marine Science and Engineering, 8(4):281, 2020b.
P. P. Mathisen and O. S. Madsen. Waves and currents over a fixed rippled bed: 2. bottom and apparent roughness experienced by currents in the presence of waves. Journal of Geophysical Research: Oceans, 101(C7):16543–16550, 1996a.
P. P. Mathisen and O. S. Madsen. Waves and currents over a fixed rippled bed: 1. bottom roughness experienced by waves in the presence and absence of currents. Journal of Geophysical Research: Oceans, 101(C7):16533–16542, 1996b.
R. Musumeci, L. Cavallaro, E. Foti, P. Scandura, and P. Blondeaux. Waves plus currents crossing at a right angle: Experimental investigation. Journal of Geophysical Research: Oceans, 111(C7), 2006.
R. E. Musumeci, V. Marletta, A. Sanchez-Arcilla, and E. Foti. A ferrofluid-based sensor to measure bottom shear stresses under currents and waves. Journal of Hydraulic Research, 56(5):630–647, 2018.
A. Nortek. Vectrino velocimeter user guide. Nortek AS, Vangkroken, Norway, 621, 2009.
J. Sleath. Turbulent oscillatory flow over rough beds. Journal of Fluid Mechanics, 182:369–409, 1987.
J. Sleath. Velocities and bed friction in combined flows. In Coastal Engineering 1990, pages 450–463. 1991.
L. Stancanelli, R. E. Musumeci, M. Stagnitti, and E. Foti. Optical measurements of bottom shear stresses by means of ferrofluids. Experiments in Fluids, 61(2):52, 2020.
B. Sumer. Lecture notes on turbulence/technical university of denmark, 2007, 2007.
P. J. Visser. Wave basin experiments on bottom friction due to current and waves. In Coastal Engineering 1986, pages 807–821. 1987.
J. Yuan and O. S. Madsen. Experimental study of turbulent oscillatory boundary layers in an oscillating water tunnel. Coastal engineering, 89:63–84, 2014.
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