This study is concerned with the effects of the flow structures including the near-wall coherent eddies in turbulent channel flows on the dispersion and deposition of nano- and micro-particles. A pseudo-spectral computational code was used for direct numerical simulations (DNS) of the Navier-Stokes equations and the corresponding time histories of the instantaneous fluid velocities were evaluated. Under the oneway coupling assumption, the trajectories of a wide range of particle sizes from 10 nm to 80 μm with dimensionless relaxation time of 2.2e−6 to 142 were obtained by solving the particle equation of motion including Stokes drag and Brownian excitations. Dispersion and deposition of particles in the turbulent flow were evaluated and the effects of turbulence structure on different size particles were studied. The simulation results showed that the concentration distribution of small particles that behave like fluid tracer particles were quite random. However, the preferential concentrations appeared as the dimensionless relaxation time increased to 2–20. In particular, the influence of coherent structures in the near-wall regions was clearly detectable on the concentration distribution of particles, as well as, in their deposition pattern. For τ+ = 20 particles due to the increase of relaxation time and inertia of particles, the small-scale turbulent features were filtered out and only the effect of large-scale turbulent eddies could be identified. For τ+ = 2–20 particles, the ensemble/time average of the position of the deposited particles showed specific spacing which was comparable to the size of the near-wall coherent structures.
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ASME 2018 5th Joint US-European Fluids Engineering Division Summer Meeting
July 15–20, 2018
Montreal, Quebec, Canada
Conference Sponsors:
- Fluids Engineering Division
ISBN:
978-0-7918-5157-9
PROCEEDINGS PAPER
Interactions of Flow Structure With Nano- and Micro-Particles in Turbulent Channel Flows
Amir A. Mofakham,
Amir A. Mofakham
Clarkson University, Potsdam, NY
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Goodarz Ahmadi,
Goodarz Ahmadi
Clarkson University, Potsdam, NY
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John McLaughlin
John McLaughlin
Clarkson University, Potsdam, NY
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Amir A. Mofakham
Clarkson University, Potsdam, NY
Goodarz Ahmadi
Clarkson University, Potsdam, NY
John McLaughlin
Clarkson University, Potsdam, NY
Paper No:
FEDSM2018-83349, V003T19A003; 4 pages
Published Online:
October 24, 2018
Citation
Mofakham, AA, Ahmadi, G, & McLaughlin, J. "Interactions of Flow Structure With Nano- and Micro-Particles in Turbulent Channel Flows." Proceedings of the ASME 2018 5th Joint US-European Fluids Engineering Division Summer Meeting. Volume 3: Fluid Machinery; Erosion, Slurry, Sedimentation; Experimental, Multiscale, and Numerical Methods for Multiphase Flows; Gas-Liquid, Gas-Solid, and Liquid-Solid Flows; Performance of Multiphase Flow Systems; Micro/Nano-Fluidics. Montreal, Quebec, Canada. July 15–20, 2018. V003T19A003. ASME. https://doi.org/10.1115/FEDSM2018-83349
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