DNS of turbulent channel flows laden with finite-size particles at high volume fractions

Abstract

Suspensions are often found in different processes and applications, e.g. sediment transport in environments or pharmaceutical engineering. The laminar regime in the semi-dilute or dense cases, non vanishing volume fraction, is usually characterized by the sometime spectacular rheological properties induced by the suspended phase. Much less is known about dissipation and mixing in the turbulent regime. The aim of the present work is to investigate the turbulent channel flow of a fluid laden with rigid spherical particles at a fixed bulk Reynolds number Reh = U0h/ν = 2800. The particle radius is selected to be 18 times smaller than the channel half-width. Fully-resolved Direct Numerical Simulations with particle tracking and Immersed Boundary Method are presented for values of the volume fraction up to φ = 0.2. As expected for “large” particles, the overall drag increases with the volume fraction. We show that the presence of the particles deeply changes flow behavior, as already evident from the mean velocity profile with the canonical regions, buffer- or log-layer, strongly altered.