The effect of polydispersity in a turbulent channel flow laden with finite-size particles

Abstract

We study turbulent channel flows of monodisperse and polydisperse suspensions of finite-size spheres by means of Direct Numerical Simulations using an immersed boundary method to account for the dispersed phase. Suspensions with 3 different Gaussian distributions of particle radii are considered (i.e. 3 different standard deviations). The distributions are centered on the reference particle radius of the monodisperse suspension. In the most extreme case, the radius of the largest particles is 4 times that of the smaller particles. We consider two different solid volume fractions, 2% and 10%. We find that for all polydisperse cases, both fluid and particles statistics are not substantially altered with respect to those of the monodisperse case. Mean streamwise fluid and particle velocity profiles are almost perfectly overlapping. Slightly larger differences are found for particle velocity fluctuations. These increase close to the wall and decrease towards the centerline as the standard deviation of the distribution is increased. Hence, the behavior of the suspension is mostly governed by excluded volume effects regardless of particle size distribution (at least for the radii here studied). Due to turbulent mixing, particles are uniformly distributed across the channel. However, smaller particles can penetrate more into the viscous and buffer layer and velocity fluctuations are therein altered. Non trivial results are presented for particle-pair statistics.

arXiv commentUnder review in the European Journal of Mechanics/B - Fluids

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Cited by in corpus (6)

• Effects of the finite particle size in turbulent wall-bounded flows of dense suspensions
• Experimental investigation of turbulent suspensions of spherical particles in a square duct
• Suspensions of finite-size neutrally-buoyant spheres in turbulent duct flow
• Relative dispersion of particle pairs in turbulent channel flow
• Finite-size spherical particles in a square duct flow of an elastoviscoplastic fluid: an experimental study
• Buoyant finite-size particles in turbulent duct flow