Sensitivities of Bottom Stress Estimation to Sediment Stratification in a Tidal Coastal Bottom Boundary Layer

Stratification Effects in a Bottom Ekman Layer

A stratified bottom Ekman layer over a nonsloping, rough surface is studied using a three-dimensional unsteady large eddy simulation to examine the effects of an outer layer stratification on the boundary layer structure. When the flow field is initialized with a linear temperature profile, a three-layer structure develops with a mixed layer near the wall separated from a uniformly stratified o...

Estimating Bottom Stress in Tidal Boundary Layer from Acoustic Doppler Velocimeter Data

Bed stresses in the bottom boundary layer of the York River estuary, Va., were estimated from 3D near-bottom velocities measured by Acoustic Doppler Velocimeters (ADVs) and also by a profiling array of electromagnetic current meters. By assuming the measurements were made in a constant stress layer, four methods of stress estimation were evaluated using ADVs: (1) direct covariance (COV) measure...

A traversing system to measure bottom boundary layer hydraulic properties

This study describes a new convenient and robust system developed to measure benthic boundary layer properties, with emphasis placed on the determination of bed shear stress and roughness height distribution within estuarine systems by using velocity measurements. This system consisted of a remotely operated motorised traverser that allowed a single ADV to collect data between 0 and 1 m above t...

On the Structure of Turbulence in the Bottom Boundary Layer of the Coastal Ocean

Six sets of particle image velocimetry (PIV) data from the bottom boundary layer of the coastal ocean are examined. The data represent periods when the mean currents are higher, of the same order, and much weaker than the wave-induced motions. The Reynolds numbers based on the Taylor microscale (Re ) are 300–440 for the high, 68–83 for the moderate, and 14–37 for the weak mean currents. The mod...

Direct measurement of hairpin-like vortices in the bottom boundary layer of the coastal ocean