Turbulence characteristics of wave-blocking phenomena. (June 2018)

• Record Type: Journal Article
• Authors: Chatterjee, Debasmita; Mazumder, B.S.; Ghosh, Subir
• Is Part Of: Applied ocean research. Volume 75(2018)
• Page Start: 15
• Page End: 36
• Publication Date: 2018-06
• Subjects: Turbulence -- Wave-blocking -- Mean velocity -- Reynolds stresses -- Spectrum analysis -- Conditional statistics; Ocean engineering -- Periodicals; 620.416205
• DOI: 10.1016/j.apor.2018.03.011
• Languages: English
• ISSNs: 0141-1187

Abstract

Highlights: Study of 'wave-blocking' for waves propagating against a current. Non-uniformity of flow with wave-blocking and wave dominated regions. Turbulence properties of counter-current propagating waves. Mean flows, Reynolds stresses, spectra and conditional statistics are analyzed. Abstract: This study explores experimentally the turbulent flow in a laboratory flume, interacting with waves propagated against the flow. It focuses a region of 'wave-blocking' for which there is a stream-wise location on the water surface, where the wave propagation velocity vanishes. The observations are corroborated by finding a critical wave frequency for a particular discharge above which the waves are effectively blocked; and verified by the dispersion relation of monochromatic wave. The counter-current propagating waves show an evolutionary change in the flow with three segmented regions, viz, flow at the upstream, blocking at the mid-stream and waves in the downstream. The instantaneous velocity data were collected using 3-D Micro-acoustic Doppler velocimeter (ADV) along the flume centerline. This study addresses the changes in the mean flows, Reynolds stresses, eddy viscosity, turbulence kinetic energy fluxes and associated contributions of burst-sweep cycles to the total Reynolds shear stress due to addition of surface waves against a current. The velocity power spectral analysis shows the energy distribution over the whole profile from upstream to downstream. The quadrant analysis is also used to highlight the turbulent event evolutions along the flow; and shows that at the wave-blocking and wave dominated regions, the contributions from ejection and sweep to the total shear stress are dominant. The changes in turbulence key parameters due to wave-blocking may affect the sediment transport in coastal region.