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Title: The fluctuation energy balance in non-suspended fluid-mediated particle transport

Here, we compare two extreme regimes of non-suspended fluid-mediated particle transport, transport in light and heavy fluids (“saltation” and “bedload,” respectively), regarding their particle fluctuation energy balance. From direct numerical simulations, we surprisingly find that the ratio between collisional and fluid drag dissipation of fluctuation energy is significantly larger in saltation than in bedload, even though the contribution of interparticle collisions to transport of momentum and energy is much smaller in saltation due to the low concentration of particles in the transport layer. We conclude that the much higher frequency of high-energy particle-bed impacts (“splash”) in saltation is the cause for this counter-intuitive behavior. Moreover, from a comparison of these simulations to particle tracking velocimetry measurements which we performed in a wind tunnel under steady transport of fine and coarse sand, we find that turbulent fluctuations of the flow produce particle fluctuation energy at an unexpectedly high rate in saltation even under conditions for which the effects of turbulence are usually believed to be small.
Authors:
 [1] ;  [2] ;  [3] ; ;  [4] ;  [5]
  1. Institute of Physical Oceanography, Ocean College, Zhejiang University, 310058 Hangzhou (China)
  2. (China)
  3. MARUM-Center for Marine Environmental Sciences, University of Bremen, 28359 Bremen (Germany)
  4. Institut de Physique de Rennes, UMR UR1-CNRS 6251, Université de Rennes 1, 35042 Rennes Cedex (France)
  5. Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, 90095-1565 Los Angeles, California (United States)
Publication Date:
OSTI Identifier:
22403208
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Fluids (1994); Journal Volume: 27; Journal Issue: 1; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 42 ENGINEERING; COLLISIONS; COMPUTERIZED SIMULATION; CONCENTRATION RATIO; DRAG; ENERGY BALANCE; FLOW RATE; FLUCTUATIONS; FLUIDS; NEUTRAL-PARTICLE TRANSPORT; PARTICLES; SAND; TURBULENCE; VELOCIMETERS; WIND TUNNELS