Date of Award

Winter 2010

Project Type

Thesis

Program or Major

Ocean Engineering

Degree Name

Master of Science

First Advisor

Diane L Foster

Abstract

The hydrodynamics of wave-current bottom boundary layers are examined with a quasi-three-dimensional non-hydrostatic bottom boundary layer model, Dune. Flow is simulated by resolving the Reynolds-Averaged Navier-Stokes equations with a k-o 2 nd order turbulence closure. The model simulations are performed for a range of theoretical and observed hydrodynamic forcing conditions to examine the boundary layer sensitivity to the wave and current forcing and bedform resolution. The model is evaluated with field observations of velocity profiles and seabed geometry collected at the Martha's Vineyard Coastal Observatory (MVCO, Edgartown, MA) in 2005 in 13 m water depth.

Model simulations forced by observed velocity time series best predicted field observations. Bichromatic wave groups simulations showed favorable results with observations, suggesting the importance of modulating velocity magnitudes. The flow field was found to be highly spatially variable in the vicinity of the bedform, emphasizing the importance of instrument location relative to bedform geometry.

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