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Título : | Settling velocity and preferential concentration of heavy particles under two-way coupling effects in homogeneous turbulence |
Autor : | Monchaux, Romain Dejoan, Anne |
Fecha de publicación : | 2017 |
Editorial : | Physics of Fluids, American Institute of Physics |
Resumen : | The settling velocity of inertial particles falling in homogeneous turbulence is investigated
by making use of direct numerical simulation (DNS) at moderate Reynolds number that
include momentum exchange between both phases (two-way coupling approach). Effects
of particle volume fraction, particle inertia, and gravity are presented for flow and particle
parameters similar to the experiments of Aliseda et al. [J. Fluid Mech. 468, 77 (2002)].
A good agreement is obtained between the DNS and the experiments for the settling
velocity statistics, when overall averaged, but as well when conditioned on the local
particle concentration. Both DNS and experiments show that the settling velocity further
increases with increasing volume fraction and local concentration. At the considered particle
loading the effects of two-way coupling is negligible on the mean statistics of turbulence.
Nevertheless, the DNS results show that fluid quantities are locally altered by the particles.
In particular, the conditional average on the local particle concentration of the slip velocity
shows that the main contribution to the settling enhancement results from the increase of
the fluid velocity surrounding the particles along the gravitational direction induced by
the collective particle back-reaction force. Particles and the surrounding fluid are observed
to fall together, which in turn results in an amplification of the sampling of particles in
the downward fluid motion. Effects of two-way coupling on preferential concentration are
also reported. Increase of both volume fraction and gravity is shown to lower preferential
concentration of small inertia particles while a reverse tendency is observed for large inertia
particles. This behavior is found to be related to an attenuation of the centrifuge effects
and to an increase of particle accumulation along gravity direction, as particle loading and
gravity become large. |
URI : | http://documenta.ciemat.es/handle/123456789/2119 |
Aparece en las colecciones: | Artículos de Energía
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