Effect of granular temperature and solid concentration fluctuation on the gas-solid drag force: A CFD test

Wang, Junwu

doi:10.1016/j.ces.2017.04.031

Cited by 22 publications

(1 citation statement)

References 25 publications

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“…The mean relative motion of particles/bubbles is responsible for the generation of fluid velocity fluctuations, which in turn modify velocity fluctuations in particles/bubbles and the mean relative motion (or drag force) between phases [42,43]. In prior works, it is shown that particle velocity fluctuations act as a source for an increase in the drag of gas-solid flows [21,24,27,44]. Most recently, Tavanashad et al [45] studied particle suspensions for a wide range of density ratio (0.001 ≤ ρ p /ρ f ≤ 1000) at Reynolds number 20.…”

Section: Particle Velocity Fluctuationsmentioning

confidence: 99%

Particle-resolved simulation of freely evolving particle suspensions: Flow physics and modeling

Tavanashad,

Passalacqua,

Subramaniam

2020

Preprint

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The objective of this study is to understand the dynamics of freely evolving particle suspensions over a wide range of particle-to-fluid density ratios. The dynamics of particle suspensions are characterized by the average momentum equation, where the dominant contribution to the average momentum transfer between particles and fluid is the average drag force. In this study, the average drag force is quantified using fully-resolved direct numerical simulation in a canonical problem: a statistically homogeneous suspension where an imposed mean pressure gradient establishes a steady mean slip velocity between the phases. The effects of particle velocity fluctuations, clustering, and mobility of particles are studied separately. It is shown that the competing effects of these factors could decrease, increase, or keep constant the drag of freely evolving suspensions in comparison to fixed beds at different flow conditions. It is also shown that the effects of clustering and particle velocity fluctuations are not independent. Finally, a correlation for interphase drag force in terms of volume fraction, Reynolds number, and density ratio is proposed. Two different approaches (symbolic regression and predefined functional forms) are used to develop the drag correlation. Since this drag correlation has been inferred from simulations of particle suspensions, it includes the effect of the motion of ⋆

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Section: Particle Velocity Fluctuationsmentioning

confidence: 99%

Particle-resolved simulation of freely evolving particle suspensions: Flow physics and modeling

Tavanashad,

Passalacqua,

Subramaniam

2020

Preprint

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Scale and structure dependent drag in gas–solid flows

Liu

Wang

2019

AIChE Journal

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Drag plays a crucial role in hydrodynamic modeling and simulations of gas–solid flows, which is significantly affected by particle Reynolds number, solid volume fraction, heterogeneity, granular temperature, particle‐fluid density ratio, and so on. To clarify and quantify the multiscale effects of these factors, large‐scale particle‐resolved direct numerical simulations of gas–solid flows with up to 115,200 freely moving particles are conducted. Both domain‐averaged kinetic properties and local averaged dimensionless drag are sampled and analyzed. It is revealed that the complex scale‐dependence of drag is attributed to the multiscale effects of heterogeneous structures and particle fluctuating velocity. The granular temperature and the scalar variance of solid volume fraction are also found to be scale‐dependent. On account of these, a new drag correlation as the function of Froude number is proposed with consideration of scale‐dependence.

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Effects of Temperature on the Filtration Characteristics of a Dual‐Layer Granular Bed Filter

et al. 2018

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The effects of temperature on the filtration efficiency and pressure drop of a duallayer granular bed filter were investigated in a hot dual-layer granular bed filter with experimental dust. Enhanced higher filtration efficiency was obtained with higher filtration temperature, and the removal efficiency of ultrafine dust was also at a high level. Simultaneously, the total pressure drop maintained at an acceptable range. The results demonstrate that the dual-layer granular bed has excellent prospects for application to low-temperature coal pyrolysis.

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Effect of granular temperature and solid concentration fluctuation on the gas-solid drag force: A CFD test

Cited by 22 publications

References 25 publications

Particle-resolved simulation of freely evolving particle suspensions: Flow physics and modeling

Particle-resolved simulation of freely evolving particle suspensions: Flow physics and modeling

Scale and structure dependent drag in gas–solid flows

Effects of Temperature on the Filtration Characteristics of a Dual‐Layer Granular Bed Filter

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