Turbulent Modulation in Particulate Flow:  A Review of Critical Variables

Saber, Ammar; Lundström, T. Staffan; Hellström, J. Gunnar I.

doi:10.4236/eng.2015.710054

Cited by 36 publications

(22 citation statements)

References 48 publications

(52 reference statements)

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“…To our regards, two major factors among all the possible ones are responsible for the mechanisms of such turbulence attenuation. Firstly, sand grains with size much larger than the Kolmogorov length scale η cause extra turbulence dissipation due to the presence of particle drag (Balachandar and Eaton 2010;Saber et al 2016). Secondly, the crossing trajectory effect, induced by heavy particles falling out from turbulent eddies (Csanady 1963), is strengthened by large slip velocity between two phases (see figure 7a).…”

Section: Two-phase Velocity Statisticsmentioning

confidence: 99%

Sand-turbulence interaction in a high-Reynolds-number turbulent boundary layer under net sedimentation conditions

Zhu

Pan

Wang

et al. 2019

International Journal of Multiphase Flow

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Section: Two-phase Velocity Statisticsmentioning

confidence: 99%

Sand-turbulence interaction in a high-Reynolds-number turbulent boundary layer under net sedimentation conditions

Zhu

Pan

Wang

et al. 2019

International Journal of Multiphase Flow

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“…В обзорной работе [4] обсуждается актуальное состояние исследований турбулентности многофазных дисперсных течений. Авторы среди перспективных направлений для фундаментальных исследований выделяют изучение механизмов модуляции турбулентности [5] частицами примеси. В работе [6] рассмотрена линейная устойчивость течения Куэтта для неоднородного распределения объемной концентрации примеси.…”

Section: Doi 1014258/izvasu(2016)1-09unclassified

On Sufficient Conditions of Stability of Convective Dispersed Flows

Popov¹,

Utemesov²,

Yudintsev³

et al. 2016

izvasu

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Представлен анализ достаточных условий гидродинамической устойчивости конвективных дисперсных течений. Актуальность подобного рода исследований обусловлена необходимостью проанализировать влияние неоднородностей, добавок или осложняющих факторов на характеристики тепломассопереноса. В частности, широко распространены в природе и технических приложениях течения двухфазных систем. Установлены достаточные условия устойчивости дисперсного течения в аналитической форме. Приведено качественное теоретическое объяснение эффекта, проявляющегося в повышении порога устойчивости для определенных значений степени дисперсности примеси. Данный эффект наблюдался ранее другими авторами с помощью численного эксперимента. Установлена явная форма зависимости критического числа Грасгофа от величины степени дисперсности примеси. Достаточные условия сформулированы в виде вариационного неравенства, свойства которого также детально обсуждаются. Установлено, что зависимость характеристик устойчивости (число Грасгофа) имеет выраженный резонансный характер, а в резонансной области порог устойчивости может повышаться в несколько раз.Ключевые слова: дисперсное течение, конвективное течение, число Грасгофа, достаточные условия устойчивости, гидродинамическая устойчивость. This paper is concerned with an analysis of sufficient conditions of hydrodynamic stability of convective disperse flows. The applicability of this kind of researches is raised with an obvious need to consider the influence of nonhomogeneous effects or flow complications on heat-mass transfer characteristics. In particular, flows of two-phase systems are common in nature and technical applications. The sufficient conditions of disperse flow stability are analytically defined. The qualitative theoretical explanation of an effect dealing with sufficient flow stabilization at certain values of dispersion degree is presented. This effect was observed earlier in numerical experiments. The analytical form of dependency of the critical Grashof number versus dispersion degree value is obtained. The sufficient conditions are formulated as a variational inequality, properties of which are thoroughly discussed. It is found that the form of dependency of stability characteristics (Grashof number) has regions corresponding to resonant behavior of fluctuation energy dissipation, and the sufficient stabilization is observed.

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“…The particles dispersion significantly affected by the particles-gas time ratio which represented by the Stokes number [10] [11]. Stokes number is an indication of the response degree of the particle to the motion alterations produced by the carrier phase turbulence [4]. The dimensionless stokes number can be defined by Equation (2).…”

Section: Particles Dispersionmentioning

confidence: 99%

“…The multiphase flow associated with turbulence is involved into many industrial applications, such as pneumatic conveying [1] and transportation of the pulverized fuel particles in a pipeline [2] [3]. The interactions between the turbulent flow and the chaotically moving particles generate a flow of complex pattern [4] [5]. These interactions are not completely clear.…”

Section: Introductionmentioning

confidence: 99%

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Solid Particles Injection in Gas Turbulent Channel Flow

Kabeel¹,

Elkelawy²,

Bastawissi³

et al. 2016

EPE

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This paper represents a review of the recent researches that investigate the behavior of the gas turbulent flow laden with solid particles. The significant parameters that influence the interactions between the both phases, such as particle size, loading ratio and the gas velocity, have been extensively reviewed. Those parameters are presented in dimensionless numbers in which the applicability of studying its effect in terms of all circumstances of the gas turbulent channel flow at different condition is possible. The represented results show that the turbulence degree is proportional to the particle size. It was found that at the most flow conditions even at low mass ratio, the particle shape, density and size significantly alter the turbulence characteristics. However, the results demonstrate that the particle Reynolds number is a vital sign: the turbulence field becomes weaker if particle Reynolds number is lower than the critical limit and vies verse. The gas velocity has a strong effect on the particles settling along the channel flow and as a result, the pressure drop will be affected.

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Turbulent Modulation in Particulate Flow: A Review of Critical Variables

Cited by 36 publications

References 48 publications

Sand-turbulence interaction in a high-Reynolds-number turbulent boundary layer under net sedimentation conditions

Sand-turbulence interaction in a high-Reynolds-number turbulent boundary layer under net sedimentation conditions

On Sufficient Conditions of Stability of Convective Dispersed Flows

Solid Particles Injection in Gas Turbulent Channel Flow

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