Some Turbulence Measurements in Water

The results of limited turbulence measurements in water in a free-surface flow are presented. A commercially available hot-wire anemometer of the constant-temperature type was used, and the recording and reduction of data were accomplished using an IBM 7094-7040 digital computing system and its peripheral analog-to-digital conversion equipment. The local temporal mean velocities, root mean squares of the turbulent velocity fluctuations, turbulent energy spectra, and auto-correlation curves were obtained directly from the digital computer. The relative turbulent intensities ranged from 4% to 5% near the water surface to 16% near the channel bottom for two cases having R of 66,200 and 91,100. Energy spectra showed that most of the turbulent energy was concentrated at frequencies less than 2 cps to 4.5 cps. The macro-scale of the turbulence in the flow direction was on the order of 80% of the depth and the turbulent microscale in that direction was approximately 10% of the depth for the experiment at the lower Reynolds number.