A complex network framework for studying particle-laden flows

Vignesh, K. Shri; Tandon, Shruti; Kasthuri, Praveen; Sujith, R. I.

doi:10.1063/5.0098917

Cited by 4 publications

(1 citation statement)

References 67 publications

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“…Clusterssmall conglomerations of particles such as molecules, nanoparticles, or colloidsare ubiquitous in natural and engineering systems. Because of their intermediate sizes between microscopic and macroscopic scales, clusters frequently serve as a bridge linking the dynamics of isolated particles and the properties of bulk matter and have attracted immense research interest due to various intriguing properties they impart to bulk materials. − Particularly, the influence of clusters on the dynamics and mechanical properties of particle suspensions has been extensively studied for decades. − Recent studies have shown that the emergence of a network-spanning cluster can significantly increase the rigidity of a system, i.e., the ability of the system to resist imposed perturbations. − These percolating clusters are responsible for diverse phenomena ranging from the jamming transition of granular packings , to shear jamming and shear thickening of particle suspensions. − …”

Section: Introductionmentioning

confidence: 99%

Heterogeneous Dynamics of Sheared Particle-Laden Fluid Interfaces with Janus Particle Doping

Qiao,

Liu,

et al. 2023

Langmuir

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The formation of particle clusters can substantially modify the dynamics and mechanical properties of suspensions in both two and three dimensions. While it has been well established that large network-spanning clusters increase the rigidity of particle systems, it is still unclear how the presence of localized nonpercolating clusters affects the dynamics and mechanical properties of particle suspensions. Here, we introduce self-assembled localized particle clusters at a fluid–fluid interface by mixing a fraction of Janus particles in a monolayer of homogeneous colloids. Each Janus particle binds to a few nearby homogeneous colloids, resulting in numerous small clusters uniformly distributed across the interface. Using a custom magnetic rod interfacial stress rheometer, we apply linear oscillatory shear to the particle-laden fluid interface. By analyzing the local affine deformation of particles from optical microscopy, we show that particles in localized clusters experience substantially lower shear-induced stretching than their neighbors outside clusters. We hypothesize that such heterogeneous dynamics induced by particle clusters increase the effective surface coverage of particles, which in turn enhances the shear moduli of the interface, as confirmed by direct interfacial rheological measurements. Our study illustrates the microscopic dynamics of small clusters in a shear flow and reveals their profound effects on the macroscopic rheology of particle-laden fluid interfaces. Our findings open an avenue for designing interfacial materials with improved mechanical properties via the control of formation of localized particle clusters.

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Section: Introductionmentioning

confidence: 99%

Heterogeneous Dynamics of Sheared Particle-Laden Fluid Interfaces with Janus Particle Doping

Qiao,

Liu,

et al. 2023

Langmuir

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Spatial evolution of multi-scale droplet clusters in an evaporating spray

Pandurangan

Sahu

2022

Physics of Fluids

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Evaporative sprays are encountered in a wide range of engineering applications. Since clustering of droplets in sprays leads to strong inhomogeneity in the spatial distribution of droplet concentration which impacts mass, momentum, and energy exchange between the spray and the surrounding flow, a detailed investigation of droplet clustering in evaporating sprays is important. In the current research work, we experimentally investigate the spatial evolution of droplet cluster characteristics in an evaporating acetone spray injected from an air-assist atomizer. The droplet size and velocity are measured using Interferometric Laser Imaging for Droplet Sizing (ILIDS) technique. In detail characterization of the droplet clusters is achieved by application of Voronoi analysis to particle image velocimetry (PIV) images of the spray droplets. This approach not only identifies the droplet clusters but also provides area, length scale, and local droplet number density within the clusters. The identified droplet clusters are multi-scale and could be classified into either large- or small-scale clusters, which scale with spray half-width and Kolmogorov length scale, respectively. Experiments are also conducted in water spray under the same operating conditions. Despite the similarity in the droplet clustering process between the two sprays at small scales of air turbulence, some distinct trends are observed for the large-scale clusters in the acetone spray. This is attributed to the higher evaporation rate of acetone droplets which promotespreferential accumulation of droplets.

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Evolution of clusters of turbulent reattachment due to shear layer instability in flow past a circular cylinder

Chopra,

Mittal,

Sujith

2024

Physics of Fluids

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We perform large eddy simulations of flow past a circular cylinder for the Reynolds number (Re) range, 2×103≤Re≤4×105, spanning subcritical, critical, and supercritical regimes. We investigate the spanwise coherence of the flow in the critical and supercritical regimes using complex networks. In these regimes, the separated flow reattaches to the surface in a turbulent state due to the turbulence generated by the shear layer instability. In the early critical regime, the turbulent reattachment does not occur simultaneously at all span locations. It occurs incoherently along the span in clusters. We treat strong surface pressure fluctuations due to the shear layer instability as extreme events and construct time-varying spatial proximity networks where links are based on synchronization between events. This analysis unravels the underlying complex spatiotemporal dynamics by enabling the estimation of characteristics of clusters of turbulent reattachment via the concept of connected components. In the critical regime, the number and size of the clusters increase with the increase in Re. At higher Re in the supercritical regime, they coalesce to form bigger clusters, resulting in increase in spanwise coherence of turbulent reattachment. We find that the size and number of clusters govern the variation of the time-averaged coefficient of drag (C¯D) in the critical and supercritical regimes. C¯D exhibits power-law distribution with the largest cluster size (C¯D∝S¯CL−25) and the most probable cluster size [C¯D∝E(SC)−25].

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A complex network framework for studying particle-laden flows

Cited by 4 publications

References 67 publications

Heterogeneous Dynamics of Sheared Particle-Laden Fluid Interfaces with Janus Particle Doping

Heterogeneous Dynamics of Sheared Particle-Laden Fluid Interfaces with Janus Particle Doping

Spatial evolution of multi-scale droplet clusters in an evaporating spray

Evolution of clusters of turbulent reattachment due to shear layer instability in flow past a circular cylinder

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