We used an experimental study to analyse the hydrodynamic conditions at an asymmetric right-angled confluence with incoming supercritical flow at higher Froude numbers (2 % Fr % 12), where dynamic, foamed standing waves form. For a phenomenological determination of the relations between the integral parameters of water flows and the characteristics of standing waves at the confluence area, we first measured water surface topographies for 168 combinations of two flows (i.e. scenarios at the confluence). Laser scanning was used to measure transversal water surface profiles, which, as a modern non-contact measurement method, allows for measurements of the phenomena with high dynamics as well as high spatial and temporal resolution. Despite its widespread use, laser scanning has not yet been used to acquire clean water topography, without any additional substances, floats, etc. Given the nature of interactions between laser beams and water body surfaces, we investigated, in the first part, the conditions under which laser scanning can be applied in water surface topography measurements. Comparing these measurements with the reference values of other measurement methods supported the first hypothesis that, both in laboratory and field measurements, laser scanning allows for a precise determination of water levels, particularly of turbulent, two-phase flows with high vertical fluctuations, i.e. complex hydraulic phenomena where other measurement methods are less successful or unsuited. In the second part we used the systematically measured water surfaces in the individual cross-sections in the confluence area for all the scenarios for determining the water level%s mean value, and by producing mesh models we constructed the topographies of standing waves. This provided an important basis for analysing confluence topography. The results supported the second hypothesis, i.e. that it is possible to record phenomenological relations between input, geometrical, and hydraulic flow parameters and the main characteristics of flow structures forming at confluences with incoming supercritical flows. The new, phenomenologically-derived equations modelling the formation of surfaces in the transversal and longitudinal directions and the fluctuation level describe the water surface topology to a satisfying degree, resulting in important information about the processes and their magnitude for engineering workWe used an experimental study to analyse the hydrodynamic conditions at an asymmetric right-angled confluence with incoming supercritical flow at higher Froude numbers (2 % Fr % 12), where dynamic, foamed standing waves form. For a phenomenological determination of the relations between the integral parameters of water flows and the characteristics of standing waves at the confluence area, we first measured water surface topographies for 168 combinations of two flows (i.e. scenarios at the confluence). Laser scanning was used to measure transversal water surface profiles, which, as a modern non-contact measurement method, allows for measurements of the phenomena with high dynamics as well as high spatial and temporal resolution. Despite its widespread use, laser scanning has not yet been used to acquire clean water topography, without any additional substances, floats, etc. Given the nature of interactions between laser beams and water body surfaces, we investigated, in the first part, the conditions under which laser scanning can be applied in water surface topography measurements. Comparing these measurements with the reference values of other measurement methods supported the first hypothesis that, both in laboratory and field measurements, laser scanning allows for a precise determination of water levels, particularly of turbulent, two-phase flows with high vertical fluctuations, i.e. complex hydraulic phenomena where other measurement methods are less successful or unsuited. In the second part we used the systematically measured water surfaces in the individual cross-sections in the confluence area for all the scenarios for determining the water level%s mean value, and by producing mesh models we constructed the topographies of standing waves. This provided an important basis for analysing confluence topography. The results supported the second hypothesis, i.e. that it is possible to record phenomenological relations between input, geometrical, and hydraulic flow parameters and the main characteristics of flow structures forming at confluences with incoming supercritical flows. The new, phenomenologically-derived equations modelling the formation of surfaces in the transversal and longitudinal directions and the fluctuation level describe the water surface topology to a satisfying degree, resulting in important information about the processes and their magnitude for engineering work
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