Remote acoustic measurements of turbulence in high-flow tidal channels during high wave conditions

Principal Investigators:

Dr. Alex Hay, Dalhousie University

Start Date: April 2018

End Date: March 2019

Many of the high-flow tidal channels targeted for in-stream hydro-electric development world-wide, are impacted by surface gravity waves incident from a large exterior basin (e.g. the Bay of Fundy/Gulf of Maine/North Atlantic). As they propagate against the outgoing tidal current, these waves grow and break, creating both wave orbital velocities comparable to the tidal current, and a source of additional turbulence at the sea surface. The associated flow conditions are complex, highly non-linear, and typically quite nasty, representing an added risk for the tidal power industry.

The present proposal is part of ongoing research collaborations into remote measurements of turbulence in high-flow, well-mixed tidal channels using acoustic Doppler techniques. Earlier work has demonstrated that, in the absence of surface gravity waves, estimates of turbulent kinetic energy dissipation rate at mid-depth are comparable to those measured directly using shear probes. More recent work is indicating that wave and turbulence motions measured with standard 4-beam Acoustic Doppler Current Profilers (ADCPs) are separable, given that certain assumptions are valid.