Measurement and prediction of bottom boundary layer hydrodynamics under modulated oscillatory flows

Electrical measurement of sediment layer thickness under suspension flows

This paper reports a new technique to measure the thickness of a layer of deposited sediment as a function of time, independent of the flow conditions or presence of suspended sediment above the layer. Small electrodes on the bottom and a reference electrode in the fluid above were used to measure the resistance of the layer with a small AC current and a bridge circuit. Using a multiplexer and ...

Chaotic motion in an oscillatory boundary layer.

The chaotic time oscillations in an incompressible fluid driven into motion by a harmonic time-varying pressure gradient is examined. Special attention is given to centrifugal destabilization of the viscous boundary layer. The basic flow is shown to be linearly unstable. For increasing modulation amplitude, the flow exhibits chaotic oscillations. The energy exchange between subharmonics and sup...

A perturbation approach to large eddy simulation of wave-induced bottom boundary layer flows

We present the development, validation, and application of a numerical model for the simulation of bottom boundary layer (BL) flows induced by arbitrary finite amplitude waves. Our approach is based on coupling a ‘near-field’ local Navier–Stokes (NS) model with a ‘far-field’ inviscid flow model, which simulates large scale incident wave propagation and transformations over a complex ocean botto...

Under-ice Boundary Layer

Sea ice is in almost constant motion in response to wind, ocean currents, and forces transmitted within the ice cover itself, thus there is nearly always a zone of sheared Sow between the ice and underlying, undisturbed ocean where turbulence transports momentum, heat, salt, and other contaminants vertically. The zone in which these turbulent Suxes occur, which can span from a few to hundreds o...

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