Direct Measurements of Reynolds Stresses and Turbulence in the Bottom Boundary Layer

Abstract

Abstract : Predictions of the ocean dynamics, sediment transport, pollutant dispersal and biological processes require knowledge on the characteristics of turbulence in the bottom boundary layer. Our goal is to: a. Measure the Reynolds stresses (free of wave contamination), velocity profile, dissipation rate, and turbulent spectra in the coastal bottom boundary layer using Particle Image Velocimetry (PIV). b. Quantify the temporal variation of turbulent stresses, production, dissipation and buoyancy flux in relation to the local oceanographic parameters, such as waves, currents, stratification, internal waves and the nature of the water-sediment interface. c. Examine the structure of the flow, vertical vorticity transport, formation and upward migrations of large coherent vortex structures. Presently there is very little information on the dynamics and impact of large coherent structure in the bottom boundary layer on turbulence and sediment entrainment. d. Study the mechanisms and extent of sediment re-suspension process by simultaneously measuring the flow structure and particle distributions. e. Use the PIV data for addressing Sub-Grid Scale Modeling issues for Large Eddy Simulation in oceanic flows.