Water current meters

The objectives of this investigation were - 1) design and build a
turbulence current meter capable of measuring velocity fluctuations in
a geophysical scale flow and 2) the measurement of such flow including
subsequent analysis of near bottom turbulence. An unique device capable
of sensing velocity fluctuations in the region 25cm above the bottom was
constructed based on concepts original to the study of turbulence. A
review of previous equipment and research is included for a comparison.
The instrument's usefulness was illustrated in the open channel flow of
a tidal estuary by its ability to detect the horizontal velocity field.
The data obtained for the turbulence shows large variation in velocity
of the lateral component on the order of 50-75% of the "mean" current
speed. Digital filtering of the data reveals distinct structures of
high energy, intermittent in their nature and analogous to "bursting".
The energy spectrum of the longitudinal component follows the predicted
slope of -1 for over two decades (.01 to 1.3 + Hz).