Modulation of turbulence by saltating particles on erodible bed surface

Zheng, Xiaojing; Feng, Shengjun; Wang, Ping

doi:10.1017/jfm.2021.329

Cited by 23 publications

(18 citation statements)

References 84 publications

(140 reference statements)

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“…In addition, the much lower mean velocity in the two-phase flow with an erodible surface than that in the single-phase flow, as shown in figure 7, is consistent with the numerical simulation results in Zheng et al. (2021 a ) and the experimental results in Li & McKenna Neuman (2012).…”

Section: Resultssupporting

confidence: 89%

“…The larger particle concentration near the wall enhances the deceleration effect on the fluid, while the particle concentration decreases and the deceleration effect on the fluid weakens with increasing height. In addition, the much lower mean velocity in the two-phase flow with an erodible surface than that in the single-phase flow, as shown in figure 7, is consistent with the numerical simulation results in Zheng et al (2021a) and the experimental results in Li & McKenna Neuman (2012).…”

Section: 1supporting

confidence: 86%

“…The near-wall motions of sand particles include not only the collision bounce, but also the impact splashing (Zheng et al. 2021 a ). Therefore, the difference between Cases 3 and 4 in figure 7 indicates that the addition of impact splashing of particles on the erodible surface weakens the mean velocity and enhances the mean shear of the fluid.…”

Section: Resultsmentioning

confidence: 99%

“…The particles move violently on the erodible surface. The particles may rebound and splash other particles after impacting the wall (Zheng, Feng & Wang 2021 a ). Therefore, the turbulence characteristics in two-phase flows are influenced by both particle and particle near-wall motions.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, Zheng, Wang & Zhu (2021b) studied the particle-wall process in a wind tunnel TBL at Re τ = 2002, and found that the mean velocity of the fluid weakened in the near-wall region due to the particle-wall process. Zheng et al (2021a) proposed the 'splashing effect' through a wall-resolved large-eddy simulation of particle-laden flows with an erodible surface at Re τ = 3730 and 4200; that is, the saltating particles enhance the outer Reynolds normal stress over a wide range of wavelengths from moderate to very large scales. Baker & Coletti (2021) investigated buoyant suspended particles (St + = 15) in a smooth-wall open channel flow at Re τ = 570, and found that the particle-wall interaction results in a decrease of the fluid turbulence intensity and shear stress in the inner region.…”

Section: Introductionmentioning

confidence: 99%

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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: 1supporting

confidence: 86%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%