caa a22 4500 606198512 CHVBK 20210128100934.0 cr unu---uuuuu 210128e20150801xx s 000 0 eng 10.1007/s00348-015-2034-3 doi (NATIONALLICENCE)springer-10.1007/s00348-015-2034-3 Cross-sectional imaging of refractive-index-matched liquid-granular flows [Elektronische Daten] [Wei-Jay Ni, Hervé Capart] In channelized liquid-granular flows, the liquid velocity, granular velocity and solid fraction all vary over transverse cross sections. A major experimental challenge is then to acquire internal measurements of these three fields. One useful first step, achievable using various materials, is to make the medium transparent by matching the refractive indexes of the liquid and granular phases. Taking full advantage of this optical access, however, requires the development of new imaging methods. In this paper, we propose a new approach applicable to steady uniform flows and spherical immersed grains. The approach combines laser scans in the transverse and longitudinal directions. Using the transverse scans, liquid and granular motions in the laser plane can be captured by particle-tracking velocimetry. The longitudinal scans, on the other hand, allow granular positions and velocities to be deduced from individual grain crossing events. These occur when flowing grains move across the laser plane and when the laser plane sweeps across stationary grains. The approach therefore applies to flows over erodible beds featuring both moving and stationary grains. Using suitable algorithms, we show how to process these scans to map granular velocity, liquid velocity and granular concentration over the entire flow cross section, at resolutions finer than the grain diameter by a factor of 10. Springer-Verlag Berlin Heidelberg, 2015 Ni Wei-Jay Department of Civil Engineering and Hydrotech Research Institute, National Taiwan University, Taipei, Taiwan aut Capart Hervé Department of Civil Engineering and Hydrotech Research Institute, National Taiwan University, Taipei, Taiwan aut Experiments in Fluids Springer Berlin Heidelberg 56/8(2015-08-01), 1-20 0723-4864 56:8<1 2015 56 348 https://doi.org/10.1007/s00348-015-2034-3 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00348-015-2034-3 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Ni Wei-Jay Department of Civil Engineering and Hydrotech Research Institute, National Taiwan University, Taipei, Taiwan aut NATIONALLICENCE 700 1- Capart Hervé Department of Civil Engineering and Hydrotech Research Institute, National Taiwan University, Taipei, Taiwan aut NATIONALLICENCE 773 0- Experiments in Fluids Springer Berlin Heidelberg 56/8(2015-08-01), 1-20 0723-4864 56:8<1 2015 56 348