Abstract

Turbulence is ubiquitous in most environmental flows. Therefore, highly resolved measurement of turbulent quantities is one of the challenges in hydraulics. As turbulence is a multi-scale physical phenomenon, the measurement resolution should be sufficient to capture all these scales. Therefore, research on turbulent flow gained momentum after the introduction of high-resolution measurement devices such as Laser Doppler Velocimeter (LDV) and Acoustic Doppler Velocimeter (ADV). In this study, a set of experiments were conducted by using ADV to measure the flow turbulence in a trapezoidal open channel on rough bed which is commonly observed in a typical riverine environment. In the experiments, vertical distribution of the turbulent quantities was investigated. The experiments are conducted by using a four component ADV with  maximum sampling frequency of 200 Hz. Measured velocity data are filtered  to eliminate the artifacts due to spikes, low correlation and SNR velocity values.  The filtered data are then analyzed to obtain the statistical parameters that characterize the flow turbulence in the water column ranging from the smallest scale to integral length scale.

Key words: Turbulence, open channel, spectral analysis.