Rf. Vanunen et al., LABORATORY MEASUREMENTS OF CURRENT FLOW USING CROSS-CORRELATION ON ACOUSTIC BACKSCATTERING FROM SUSPENDED SEDIMENTS, The Journal of the Acoustical Society of America, 104(3), 1998, pp. 1345-1355
The application of acoustic backscattering, for measuring near-bed hig
h-resolution profiles of suspended sediment concentration and particle
size, has advanced substantially in recent years. To interpret these
suspension observations and link them with the hydrodynamics, similarl
y detailed flow observations would be advantageous. In the present wor
k backscattering from suspensions of marine sediments has been investi
gated to examine the potential of using the backscattered signal to al
so measure high-resolution near-bed vertical profiles of horizontal cu
rrent flow. The approach adopted has been to attempt to utilize the te
mporal coherence in the suspension field, and to employ cross correlat
ion of the backscattered signal between pairs of horizontally separate
d transducers to measure current profiles. To investigate this techniq
ue a series of laboratory measurements have been conducted for a varie
ty of experimental arrangements, and the outcome from these measuremen
ts is reported in the present work. An examination of the suspension h
eld has been conducted, and cross correlations between pairs of transd
ucers investigated. Using cross-correlation time lags, current profile
s have been calculated, and the results assessed using laser Doppler f
low measurements. Comparison of the acoustic cross-correlation flow me
asurements with the Doppler reference measurements show a high degree
of agreement, and strongly support the use of the cross-correlation ap
proach to accurately measure vertical profiles of the mean horizontal
current. (C) 1988 Acoustical Society of America. [S0001-4966(98)00309-
9].