scholarly journals Near-wall dynamics of inertial particles in dilute turbulent channel flows

2019 ◽  
Vol 31 (6) ◽  
pp. 063302 ◽  
Author(s):  
L. F. Mortimer ◽  
D. O. Njobuenwu ◽  
M. Fairweather
Keyword(s):  
Channel Flows ◽  
Inertial Particles ◽  
Turbulent Channel Flows ◽  
Near Wall

On the near-wall structures and statistics of fluctuating pressure in compressible turbulent channel flows

2020 ◽  
Vol 32 (11) ◽  
pp. 115121 ◽  
Author(s):  
Jiupeng Tang ◽  
Zhiye Zhao ◽  
Zhen-Hua Wan ◽  
Nan-Sheng Liu
Keyword(s):  
Channel Flows ◽  
Fluctuating Pressure ◽  
Turbulent Channel Flows ◽  
Wall Structures ◽  
Near Wall

Interactions of Flow Structure With Nano- and Micro-Particles in Turbulent Channel Flows

2018 ◽  
Author(s):  
Amir A. Mofakham ◽  
Goodarz Ahmadi ◽  
John McLaughlin
Keyword(s):  
Relaxation Time ◽  
Coherent Structures ◽  
Concentration Distribution ◽  
Channel Flows ◽  
Small Scale ◽  
Turbulence Structure ◽  
Micro Particles ◽  
Turbulent Channel Flows ◽  
Wide Range ◽  
Near Wall

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.

An improved near-wall treatment for turbulent channel flows

2011 ◽  
Vol 25 (1) ◽  
pp. 41-46 ◽  
Author(s):  
Najla El Gharbi ◽  
Rafik Absi ◽  
Ahmed Benzaoui ◽  
Rachid Bennacer
Keyword(s):  
Channel Flows ◽  
Turbulent Channel Flows ◽  
Near Wall

Numerical prediction on deposition of micro-particulate matter in turbulent channel flows

2015 ◽  
Vol 26 (12) ◽  
pp. 1550134 ◽  
Author(s):  
Bing Wang ◽  
Jing Lin
Keyword(s):  
Particulate Matter ◽  
Particle Deposition ◽  
Prediction Models ◽  
Stokes Number ◽  
Particle Dispersion ◽  
Channel Flows ◽  
Inertial Particles ◽  
Navier Stokes Equation ◽  
Deposition Rates ◽  
Turbulent Channel Flows

A direct numerical simulation of Navier–Stokes equation coupled to the Lagrangian tracking of individual particles was used to predict the dispersion of deposited micro-particulate matter in turbulent channel flows on the walls. The different interaction conditions between particles and walls were considered for particles with Stokes numbers ranging from 0.1 to 104. The particle deposition rates were predicted accurately because of the accurate calculation of turbulence and particle dispersion. It was found the interaction between the turbulent particles and the walls determined the re-entrainment mechanism of inertial particles away from the wall. The dispersion of deposition of particles were independent of the wall conditions in the partial diffusional and whole diffusion-impaction regime, consistent with a log–log law with particle Stokes number, which was found to be [Formula: see text]. The deposition rate decreased with decreasing adhesion of the wall in the inertia-moderated regime. The present results may be helpful for establishing and evaluating accurate prediction models of micro-particle deposition rates in various engineering applications.

Reynolds number effects in the near-wall region of turbulent channel flows

2001 ◽  
Vol 13 (6) ◽  
pp. 1755-1767 ◽  
Author(s):  
M. Fischer ◽  
J. Jovanović ◽  
F. Durst
Keyword(s):  
Reynolds Number ◽  
Channel Flows ◽  
Wall Region ◽  
Turbulent Channel Flows ◽  
Reynolds Number Effects ◽  
Near Wall
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