Water surface fluctuations of standing waves at the supercritical confluence flow
- Authors: Gašper Rak, Marko Hočevar, Franci Steinman
- Citation: Acta hydrotechnica, vol. 30, no. 53, pp. 107-120, 2017.
- Abstract: Two-phase flow often occurs in supercritical flows, accompanied by a highly dynamic, non-stationary water surface. Determining the average water surface profile, especially with higher spatial resolution, is practically impossible using conventional measurement methods. In the analysis of supercritical confluence flow, where standing waves with high vertical dynamic of water surface are formed, laser scanning was used to measure the free-water surface. Average profile as well as fluctuations of water surface can be determined with processing of (processed) measurements of this non-contact measurement method, as presented in this paper. The results contribute to wider use of this measurement method, which provides important information on water flow properties to many fields of hydro-engineering. Flow conditions are shown at confluences, where measurements of water surface dynamics in measured cross-section for 168 combinations of two flows with high values of Froude numbers (2 < Fr < 12) were used to determine the envelopes of vertical water surface fluctuation around mean value. The integration of several measured cross-sections enabled the construction of the undulating water surface with several peaks of standing waves in the confluence area. Phenomenological relations were developed between input flow parameters and mean water levels as well as fluctuations of water surface for areas of standing waves.
- Keywords: confluence, supercritical flow, two-phase flow, fluctuations of water, laser scanning
- Full text: a30gr.pdf
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