Turbulence measurements in a meandering laboratory river channel

Measurements of turbulence characteristics were performed in a laboratory meandering river channel. The measurements were performed using a single hot-film anemometer at five sections beginning from the apex of the first bend to the apex of the second bend. Measurements were made at different depths along the verticals at different positions across a cross section. The data gathered in this study included longitudinal velocity, relative turbulent intensity, auto-correlation functions, energy spectra, and normalized macroscale and microscale. The objectives of presenting and interpreting the data are to understand how the turbulence is affected by channel curvature and also how it changes with the depth. The average flow depth for the meandering channel was 0.40 ft. The average width of the channel was 5.42 ft. The average flow speed was 1.61 fps. The vertical profiles of the longitudinal velocity showed that the mean velocity profiles do not follow a logarithmic pattern in the upper part of the flow. For all the stations the relative turbulent intensity normalized with local mean velocity decreased with increasing distance from the bottom of the channel except near the water surface in the same location. The variation of the turbulent intensity with the relative depth was found to be non-logarithmic for all sections. The autocorrelation coefficients decreased from unity for no time lag to zero for a time lag on the order of 0.5 seconds. The energy spectra showed that most of the energy is concentrated in frequencies less than 10 Hz. The plots of normalized microscale show little depthwise variations. The plots of normalized macroscale show an S-shaped pattern in all the data