Abstract
Vertical profiles of vertical turbulence intensity and vertical sediment fluxes were collected by an acoustic coherent Doppler profiler at two locations: Queensland Beach (Nova Scotia), and Duck (North Carolina). Observations of the turbulence intensity over different bed states (irregular ripples, cross ripples, linear-transition ripples, and flat bed) reveal that the near-bed turbulence levels are strongly affected by bed forms. This study examines the mechanisms of distributing suspended sediments and generating near-bed turbulence for the four bed states based on the characteristics of two previously observed mechanisms: diffusion and vortex shedding. Wave-phase averages of turbulence intensity, suspended sediment concentration, and suspended sediment fluxes are compared to vortex shedding and diffusion signatures. Evidence of vortex shedding is found for the low-energy ripples, but no signatures of diffusion are observed. Two diffusion models including a bed stress model, and an eddy diffusion model are found to predict near-bed turbulence levels reasonably well, but predictions are inconsistent with the trend of the data. A vortex-shedding model [J. F. A. Sleath, J. Fluid Mech. 182, 369–409 (1987)] predicts the vertical structure of the turbulence for rippled beds when the ripple wavelength is used as a ripple roughness.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
