Falling clouds of particles with finite inertia in viscous flows

Chen, Pinzhuo; Chen, Sheng; Li, Shuiqing

doi:10.1063/5.0042658

Cited by 7 publications

(2 citation statements)

References 45 publications

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“…In other words, in suspensions of small particles the clusters dominate the settling dynamics, whereas the settling in suspensions of larger particles is dominated by hindered settling. The impact of clusters on particle settling may be related to the different shape, particle concentration, and longevity of the clusters, which in turn may depend on how particles are coupled to fluid motion (Chen et al., 2021; Nitsche & Batchelor, 1997; Pignatel et al., 2011).…”

Section: Discussionmentioning

confidence: 99%

Experimental Measurement of Enhanced and Hindered Particle Settling in Turbulent Gas‐Particle Suspensions, and Geophysical Implications

et al. 2023

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The dynamics of geophysical dilute turbulent gas‐particles mixtures depends to a large extent on particle concentration, which in turn depends predominantly on the particle settling velocity. We experimentally investigate air‐particle mixtures contained in a vertical pipe in which the velocity of an ascending air flux matches the settling velocity of glass particles. To obtain local particle concentrations in these mixtures, we use acoustic probing and air pressure measurements and show that these independent techniques yield similar results for a range of particle sizes and particle concentrations. Moreover, we find that in suspensions of small particles (78 μm) the settling velocity increases with the local particle concentration due to the formation of particle clusters. These clusters settle with a velocity that is four times faster than the terminal settling velocity of single particles, and they double settling speeds of the suspensions. In contrast, in suspensions of larger particles (467 μm) the settling velocity decreases with increasing particle concentration. Although particle clusters are still present in this case, the settling velocity is decreased by 30%, which is captured by a hindered settling model. These results suggest an interplay between hindered settling and cluster‐induced enhanced settling, which in our experiments occur respectively at Stokes number O(100) and O(1). We discuss implications for volcanic plumes and pyroclastic currents. Our study suggests that clustering and related enhanced or hindered particle settling velocities should be considered in models of volcanic phenomena and that drag law corrections are needed for reliable predictions and hazard assessment.

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Section: Discussionmentioning

confidence: 99%

Experimental Measurement of Enhanced and Hindered Particle Settling in Turbulent Gas‐Particle Suspensions, and Geophysical Implications

et al. 2023

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“…The equivalent hydraulic radius R c = Na (6v/5V), and V is the velocity of cluster. We also consider the cluster settling model in non-Newtonian fluids (Xu, Song et al, 2019) and Newtonian fluids (Chen, Chen et al, 2021).…”

Section: The Cluster Dynamic Behavior Approachmentioning

confidence: 99%

Study on particle cluster dynamics behavior in settling and the influence by fiber barrier

Bai

et al. 2022

Front. Mater.

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The dispersion of particle clusters is relevant to a high concentration carrying fluid such as fracturing and drilling fluid, and the fiber-containing fluid could improve the carrying performance of particles. In the present study, the settling dynamics behavior of clusters is investigated using the CFD-DEM method. The numerical simulation method employed was able to accurately predict the deformation and velocity change rules, which express the cluster settling dynamics behavior. The velocity variation of particles is affected by hindrance and contact inside the cluster, and the velocity contrast leads to particle leakage and cluster deformation. The cluster will have regular shape changes and break up in the settlement process under gravity and fluid drag force. According to the sensitivity parameter analysis, the deformation of clusters is mainly affected by the fluid rheological properties. Different from glycerol, the settling cluster in viscoelastic HPG has a more complex dynamic behavior and a better fiber barrier effect. The fiber barrier between particles in the cluster can be regarded as a weakly constrained fiber grid structure. Due to the contact force, fiber grid structure formed in the cluster could effectively restrain the shape change and break up trend in the settlement process. The design also considers the influence of fiber and HPG concentration, and we analyze the settling velocity of the mixed-fiber cluster. Overall, the research on the cluster settling dynamics behavior is helpful in analyzing the effect of fiber-containing fluid in the carrying performance of particles.

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Particle-resolved simulation on viscous flow past random and ordered arrays of hot ellipsoidal particles

Chen

et al. 2021

International Journal of Multiphase Flow

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Falling clouds of particles with finite inertia in viscous flows

Cited by 7 publications

References 45 publications

Experimental Measurement of Enhanced and Hindered Particle Settling in Turbulent Gas‐Particle Suspensions, and Geophysical Implications

Experimental Measurement of Enhanced and Hindered Particle Settling in Turbulent Gas‐Particle Suspensions, and Geophysical Implications

Study on particle cluster dynamics behavior in settling and the influence by fiber barrier

Particle-resolved simulation on viscous flow past random and ordered arrays of hot ellipsoidal particles

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