1 research outputs found
Simulating turbulence measurements in high flow ocean regions with an acoustic backscatter model
Measurements of ocean turbulence are essential in understanding ocean mixing
and bottom stress. These measurements of turbulence are also needed when es-
tablishing loading forces on marine structures especially where they are deployed in
regions of high turbulence. In particular, there is a need for accurate measurements
of turbulence in regions where in-stream tidal turbines are being deployed. This
study reports on two broadband Doppler sonar systems, the 1 MHz Signature Nortek
AD2CP and the Workhorse 600 kHZ ADCP. The ability of these devices to collect
accurate velocity measurements in tidal regions has been tested in the field (McMillan
et al., 2016; Shcherbina et al., 2018); however we lack a way to directly validate the
accuracy of these field measurements. This difficulty is addressed through the use of
a three-dimensional numerical model of acoustic backscatter (Zedel, 2008, 2015). De-
velopments to the model were completed for the present turbulence study, including
the integration of data from a computational fluid dynamics simulation and an up-
grade to the signal processing technique. The model can be used to simulate Doppler
Sonar measurements in flows similar to those observed in regions where in-stream
tidal turbines are deployed. The resulting model simulations show that turbulent
structure can be resolved by both broadband Doppler systems, but that the 1 MHz
Nortek AD2CP, which has a faster sampling rate, yields higher resolution results.
This thesis discusses the uncertainty of the simulated results using quantitative tools
and draws comparisons to an experimental study published by McMillan et al. (2016)