Laser ranging measurements of turbulent water surfaces

• Published in: European journal of mechanics, B, Fluids B, Fluids, 2020-05, Vol.81, p.165-172
• Main Authors: Rak, Gašper, Steinman, Franc, Hočevar, Marko, Dular, Matevž, Jezeršek, Matija, Pavlovčič, Urban
• Format: Article
• Language: English
• Subjects: Free surface; High-speed camera; Laser triangulation; LIDAR; Non-stationary surface; Turbulence
• ISSN: 0997-7546; 1873-7390
• DOI: 10.1016/j.euromechflu.2020.02.001

Laser ranging is a measurement method, applied in a wide range of applications. In this study, laser ranging is used to measure the height of turbulent water flows. Measurements were performed in three cross sections of a confluence where a tributary flow meets the main flow. Both flows exhibited high Reynolds and Froude numbers where the free-water surface profiles were turbulent, non-stationary and non-homogeneous. Measurements were taken using a commercial LIDAR and a high-speed camera. The high-speed camera was operated on the principle of laser triangulation, using only the illumination from the LIDAR laser beam. Since, no other state-of-the-art method for measuring instantaneous water surface profiles exists, LIDAR and triangulation methods could only be compared with each other. The results show good agreement between both methods for the average turbulent water profile and fair agreement for instantaneous profiles. Presented herein is an explanation of these results. •Simultaneous profiling of turbulent flows with two laser ranging measurement methods.•Comparison of LIDAR and laser triangulation method using a high-speed camera.•Instantaneous measurement of water surface profiles of turbulent, highly-aerated flows.•A deeper understanding of a laser beam scattering by the aerated water surface.