Suspensions of finite-size neutrally-buoyant spheres in turbulent duct flow

Abstract

We study the turbulent square duct flow of dense suspensions of neutrally-buoyant spherical particles. Direct numerical simulations (DNS) are performed in the range of volume fractions $\varphi =0-0.2$, using the immersed boundary method (IBM) to account for the dispersed phase. Based on the hydraulic diameter a Reynolds number of $5600$ is considered. We report flow features and particle statistics specific to this geometry, and compare the results to the case of two-dimensional channel flows. In particular, we observe that for $\varphi =0.05$ and $0.1$, particles preferentially accumulate on the corner bisectors, close to the duct corners as also observed for laminar square duct flows of same duct-to-particle size ratios. At the highest volume fraction, particles preferentially accumulate in the core region. For channel flows, in the absence of lateral confinement particles are found instead to be uniformily distributed across the channel. We also observe that the intensity of the cross-stream secondary flows increases (with respect to the unladen case) with the volume fraction up to $\varphi =0.1$, as a consequence of the high concentration of particles along the corner bisector. For $\varphi =0.2$ the turbulence activity is strongly reduced and the intensity of the secondary flows reduces below that of the unladen case. The friction Reynolds number increases with $\varphi$ in dilute conditions, as observed for channel flows. However, for $\varphi =0.2$ the mean friction Reynolds number decreases below the value for $\varphi =0.1$.

arXiv commentSubmitted to Journal of Fluid Mechanics

References in corpus (17)

• An Immersed Boundary Method with Direct Forcing for the Simulation of Particulate Flows
• Turbulent channel flow of dense suspensions of neutrally-buoyant spheres
• Collision model for fully-resolved simulations of flows laden with finite-size particles
• Transition to turbulence in particulate pipe flow
• Sedimentation of finite-size spheres in quiescent and turbulent environments
• Laminar, turbulent and inertial shear-thickening regimes in channel flow of neutrally buoyant particle suspensions
• Shear thickening in non-Brownian suspensions: an excluded volume effect
• Inertial migration of spherical and oblate particles in straight ducts
• The effect of particle density in turbulent channel flow laden with finite size particles in semi-dilute conditions
• Universal Scaling Laws for Dense Particle Suspensions in Turbulent Wall-Bounded Flows
• Drag reduction in turbulent channel flow laden with finite-size oblate spheroids
• Microstructure and rheology of finite inertia neutrally buoyant suspensions
• Aspect ratio effect on particle transport in turbulent duct flows
• Rheology of confined non-Brownian suspensions
• Deformation and orientation statistics of neutrally buoyant sub-Kolmogorov ellipsoidal droplets in turbulent Taylor-Couette flow
• Turbulent channel flow of a dense binary mixture of rigid particles
• The effect of polydispersity in a turbulent channel flow laden with finite-size particles

Cited by in corpus (6)

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• From nearly homogeneous to core-peaking suspensions: insight in suspension pipe flows using MRI and DNS
• Secondary flows drive triboelectric powder charging in pneumatic conveying
• Results from Particle-Resolved Simulations