Role of viscosity in the preferential concentration of heated, bidispersed particles

Saieed, Ahmed; Rahman, Mustafa Mutiur; Hickey, Jean-Pierre

doi:10.1016/j.ijmultiphaseflow.2022.104185

Cited by 5 publications

(11 citation statements)

References 44 publications

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“…A similar trend was witnessed in Saieed et al. (2022), where in Gas 1 and Liquid 1, larger particles depicted higher RDF than smaller particles, while an opposite pattern was observed in the other cases. This is a turbulence-driven effect (as discussed later), thus we are not concerned with whether smaller or larger particles show greater clustering.…”

Section: Resultssupporting

confidence: 86%

“…The radii of the two particle species were and , which are identical to the test case Gas 2 of Saieed et al. (2022). From here on, the two particle sizes will be referred to as small and large particles in the text.…”

Section: Methodsmentioning

confidence: 86%

“…It was found in one-way momentum coupling that particles of different sizes congregate in a range of strain rate () and vorticity () zones; see figures 14 and 15 of Saieed et al. (2022). In two-way coupling, we expect the local and fluctuation to be damped by the particles as and are the symmetric and skew-symmetric parts of , respectively.…”

Section: Resultsmentioning

confidence: 97%

“…In a recent analysis, we observed higher clustering in a heated bidispersed particle-laden flow when variable viscosity was used in comparison to constant viscosity cases (Saieed, Rahman & Hickey 2022). It was found that as the gas temperature-driven viscosity increased, the clustering of smaller particles increased even when their based on the Kolmogorov scale () decreased from to – a trend opposite to the conventional assumption.…”

Section: Introductionmentioning

confidence: 81%

“…Particle clustering was quantified with the radial distribution function (RDF), which counts the number of particles within a certain radial distance from a reference particle (for details, see Saieed et al. 2022). This analysis is explained in § 3.1.…”

Section: Methodsmentioning

confidence: 99%

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Viscosity-modulated clustering of heated bidispersed particles in a turbulent gas

Saieed,

Hickey

2024

J. Fluid Mech.

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Clustering of externally and evenly heated particles is enhanced by the increased viscosity of heated fluid in the vicinity of these clusters – a phenomenon known as viscous capturing (VC). Herein we study, via direct numerical simulations of decaying turbulence, the effect of temperature-driven viscosity on clustering with different particle loading densities. We employ a two-way momentum and energy coupling, and gas viscosity is modelled by a power law to understand the role of the increased drag and particle back-reaction force on the clustering intensity. For the continuum and dispersed phases, Eulerian and Lagrangian point particle schemes have been used, neglecting inter-particle collisions. We found that the enhanced viscosity-driven clustering is a strong function of particle loading density, as the increase in particle number density enables the formation of large uneven clusters before heating, which is the main condition for VC to take effect. Higher number density should result in greater turbulence modulation and negate local temperature-based viscous effects leading to VC. However, due to higher local particle number density in the clusters and interphase heat transfer, increased drag force prevails in such cases and delivers excessive clustering. By sampling conditionally the particle velocity and temperature inside the clusters, it is found that the thermodynamic and kinematic properties of the particles in the clusters are highly correlated, and this correlation increases with the particle loading density. Therefore, based on the particle number density, temperature-based viscosity can enhance considerably the clustering of heated particles and alter the effect of particles on the underlying turbulence.

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Section: Resultssupporting

confidence: 86%

Section: Methodsmentioning

confidence: 86%

Section: Resultsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 81%

Section: Methodsmentioning

confidence: 99%

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Viscosity-modulated clustering of heated bidispersed particles in a turbulent gas

Saieed,

Hickey

2024

J. Fluid Mech.

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Particle transport in fractured geo-energy reservoirs considering the effect of fluid inertia and turbulent flow: A review

Edirisinghe,

Perera,

Elsworth

et al. 2024

Journal of Rock Mechanics and Geotechnical Engineering

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Viscous capturing of heated particles in one- and two-way coupled turbulence

Saieed,

Hickey

2023

Progress in Canadian Mechanical Engineering. Volume 6

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Inertial particles are known to form clusters in turbulence. In this regard, the previous literature employs a dimensionless parameter, Stokes number (St), for characterizing particle clustering. However, it was recently found that in heated particle-laden flows, temperature-driven fluid viscosity causes the particle clustering to depart from their St based behaviour, and deliver higher clustering than the classical predictions. This is due to a phenomenon called viscous capturing (VC), where particles locally get captured by viscous gas clouds upon heating which results in greater clustering. The aim of this study is to use Direct Numerical Simulations (DNS) for testing VC in one-way coupling (OWC) and two-way coupling (TWC) in momentum, to understand the validity of VC. It is found that the VC holds well even in TWC, where particle are capable of resisting VC. Hence, VC should be considered an important parameter in clustering sensitive thermal applications, along with St.

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Role of viscosity in the preferential concentration of heated, bidispersed particles

Cited by 5 publications

References 44 publications

Viscosity-modulated clustering of heated bidispersed particles in a turbulent gas

Viscosity-modulated clustering of heated bidispersed particles in a turbulent gas

Particle transport in fractured geo-energy reservoirs considering the effect of fluid inertia and turbulent flow: A review

Viscous capturing of heated particles in one- and two-way coupled turbulence

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