Near-wall turbulence modulation by small inertial particles

Costa, Pedro; Brandt, Luca; Picano, Francesco

doi:10.1017/jfm.2021.507

Cited by 29 publications

(31 citation statements)

References 33 publications

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“…In Cases 3 and 4, the trends of the Reynolds normal stress of the particle phase are consistent qualitatively (as well as consistent with the results in Costa et al. 2018, 2021), but the magnitude of Case 4 is slightly smaller than that of Case 3 because more kinetic energy is lost during the collision of particles with the erodible surface in Case 4 (not only losing kinetic energy during collision with the wall but also transferring energy to stationary particles on the sand bed) as compared to the solid wall in Case 3.…”

Section: Resultssupporting

confidence: 89%

“…In addition, the increased Reynolds shear stress in the particle-laden flow with an erodible surface as compared to the particle-free flow is consistent qualitatively with the interface-resolved DNS two-phase flow results in Costa et al. (2020, 2021) for small-inertia particles.…”

Section: Resultssupporting

confidence: 87%

“…As expected, the comparison of the results in the three cases of the particle-laden flows is consistent with that of the Reynolds normal stresses. The trend of the particle shear stress in Case 2 is consistent at a qualitative level with that in Zhu et al (2019), and the trends in Cases 3 and 4 are consistent with the results of Costa et al (2021).…”

Section: 1supporting

confidence: 80%

“…(2019) also showed an increased velocity near the wall and decreased velocity far away from the wall through PIV visualization experiments in a horizontal channel two-phase flow with , and , . Recently, Costa, Brandt & Picano (2020, 2021) used interface-resolved direct numerical simulation (DNS) to study near-wall turbulence modulation by small inertial particles under three bulk solid mass fractions (, 3.37 % and 33.7 %) at , and found that the velocity is attenuated in the outer region at higher mass fractions. In addition, two-phase flow numerical simulations with different particle volume fractions, particle densities and wall roughnesses, by Wu et al.…”

Section: Introductionmentioning

confidence: 90%

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Experimental investigation of the effects of particle near-wall motions on turbulence statistics in particle-laden flows

2022

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Experiments on particle-free and particle-laden flows with the same incoming velocity were conducted in a horizontal wind tunnel. Three cases of particle-laden flows with different degrees of particle near-wall motions and similar particle volume fractions, including top-release particles, local-laying sand beds and global-laying sand beds, were designed to investigate the effects of collision bounces and impact splashing on turbulence statistics. The top-released particles accelerate the fluid during gravitational settling, but weaken the intensity and reduce the probability of ‘ejection’ and ‘sweep’ events. This leads to a weakened Reynolds stress and a decreased scale of the outer spectral peak at the centre of the logarithmic region, indicating a concentration of energy at small scales. In contrast, the collision bounce and impact splashing slow the fluid but promote the ‘ejection and sweep’ cycle with larger intensity, and thus enhance the Reynolds stress. Meanwhile, the bouncing and splashing generate ascending particles that transport the kinetic energy upwards, resulting in more energetic very-large-scale motions further from the wall. This study reveals the importance of particle motions to turbulence, and contributes to a further insight into the interactions between particles and turbulence in two-phase flows with erodible surfaces.

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Section: Resultssupporting

confidence: 89%

Section: Resultssupporting

confidence: 87%

Section: 1supporting

confidence: 80%

Section: Introductionmentioning

confidence: 90%

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Experimental investigation of the effects of particle near-wall motions on turbulence statistics in particle-laden flows

2022

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“…2001; Portela & Oliemans 2003; Dritselis & Vlachos 2008; Nasr, Ahmadi & Mclaughlin 2009; Dritselis & Vlachos 2011; Kuerten, van der Geld & Geurts 2011; Zhao, Andersson & Gillissen 2013; Fox 2014; Richter 2015; Capecelatro, Desjardins & Fox 2016; Li, Luo & Fan 2016 a ; Capecelatro, Desjardins & Fox 2018; Wang & Richter 2019; Costa, Brandt & Picano 2020; Zhou et al. 2020; Costa, Brandt & Picano 2021). Previous studies investigated the effects of particles on the properties of near-wall turbulence, including turbulent intensity (Rashidi et al.…”

Section: Introductionmentioning

confidence: 99%

Two-way coupled turbulent particle-laden boundary layer combustion over a flat plate

et al. 2022

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In the present study, turbulent particle-laden boundary layer combustion over a flat plate is investigated using direct numerical simulation (DNS). A two-way coupled Eulerian–Lagrangian point particle method is used for the solid phase. The effects of particle Stokes numbers, mass loadings and chemical reactions on the interactions between particles and boundary layer turbulence in the near-wall region are explored. It was found that particle heat transfer is dominant over wall heat transfer in the reacting case with heavy particles and large mass loadings, resulting in a lower fluid temperature. Particle accumulation due to the turbophoresis effect in the near-wall region is observed, which is more prominent in the cases with a large Stokes number. The turbophoresis effect is examined via the magnitude of streamwise vorticity $\varOmega _x$ . It is shown that $\varOmega _x$ is attenuated by heavy particles, and the attenuation increases with increasing mass loadings. Therefore, particle wall–accumulation is less prominent in the cases with large mass loadings. Compared with the non-reacting cases, the distribution of particles is more inhomogeneous for the reacting cases, where the particles move faster due to intense reactions with increasing wall-normal distance. Finally, the flow topologies and the Reynolds stress anisotropy are examined to understand turbulence modulation by combustion and particles. It was suggested that light particles augment the vortex-dominant topologies, whereas heavy particles have an opposite effect. The anisotropy mapping of the Reynolds stress shows that the flows become more one-dimensional in the near-wall region for the cases with combustion and/or large mass loadings.

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A multiple-time-step integration algorithm for particle-resolved simulation with physical collision time

Zhu

Zheng

2023

International Journal of Multiphase Flow

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Near-wall turbulence modulation by small inertial particles

Abstract: Abstract

Cited by 29 publications

References 33 publications

Experimental investigation of the effects of particle near-wall motions on turbulence statistics in particle-laden flows

Experimental investigation of the effects of particle near-wall motions on turbulence statistics in particle-laden flows

Two-way coupled turbulent particle-laden boundary layer combustion over a flat plate

A multiple-time-step integration algorithm for particle-resolved simulation with physical collision time

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