Large-scale structures of wall-bounded turbulence in single- and two-phase flows: advancing understanding of the atmospheric surface layer during sandstorms

Liu, Hongyou; Zheng, Xiaojing

doi:10.1017/flo.2021.6

Cited by 25 publications

(10 citation statements)

References 164 publications

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“…1979; Dharmarathne et al. 2016; Zhang, Hu & Zheng 2018; Chowdhuri, Todekar & Prabha 2021; Liu & Zheng 2021) that are similar to structures in the velocity field. Studying the influence of the fluid on the discrete particle phase and then revealing its structural characteristics in the high-Reynolds-number particle-laden wall-bounded turbulence can not only provide in-depth information on the transport behaviour of the fluid with respect to the particle but can also help to further reveal the physical mechanism of particle–turbulence interactions.…”

Section: Introductionmentioning

confidence: 95%

The effect of turbulent motions on particle spatial distribution in high-Reynolds-number particle-laden flows

He,

Liu

2023

J. Fluid Mech.

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The spatial relationship between turbulent and particle concentration structures is investigated based on the turbulent velocity and particle concentration data obtained synchronously at the Qingtu Lake Observation Array site. In addition to the observation of particle concentration structures that contain not only large-scale coherence but also significant energy in the high-Reynolds-number atmospheric surface layer (ASL), the scale of turbulent motions that have the most significant coherence with particle concentration is found to follow a 1/2 power scaling law with the local height and ASL thickness. Moreover, large-scale turbulent velocity fluctuations have a significant amplitude modulation effect on particle concentration fluctuations, but the modulating influence is different for small dust particles and large saltating particles. Based on the interphase amplitude modulation, there exists a particle–turbulence structure phase difference that varies with height, which further makes the structure inclination angle of the particle concentration larger than that of the turbulence. In this scenario, a conceptual model reflecting the relationship between the two is proposed, and a quantitative formulation is further derived and found to be in good agreement with the experimental results. These findings and the proposed model contribute insights into particle–turbulence interactions, thereby providing theoretical support for a unified model of turbulence dynamics and particle kinematics.

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Section: Introductionmentioning

confidence: 95%

The effect of turbulent motions on particle spatial distribution in high-Reynolds-number particle-laden flows

He,

Liu

2023

J. Fluid Mech.

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“…A detailed description of the geographic, meteorological and instrument configuration conditions at the QLOA site is given in our previous works (e.g. Zheng 2013;Zhang & Zhou 2020;Liu & Zheng 2021).…”

Section: Descriptions Of the Datasetsmentioning

confidence: 99%

Multifield intermittency of dust storm turbulence in the atmospheric surface layer

2023

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Dust storms are typical dispersed two-phase atmospheric turbulence involving electrified charged dust particles. Previous observations have demonstrated that clean-air atmospheric turbulence is strongly intermittent. However, the intermittency of the wind velocity, concentration of dust particles with a diameter smaller than $10\ \mathrm {\mu }{\rm m}$ (PM10) and electric fields, known as multifield intermittency, has not been reported or characterized yet. Here, we quantify the small-scale multifield intermittency of dust storms using datasets obtained from the Qingtu Lake Observation Array and a wavelet-based data analysis technique. The results indicate that the probability density functions of the multifield increments are scale dependent, and the scaling exponents of the multifield structure functions exhibit anomalous scaling, suggesting that the multiple fields in dust storms are also highly intermittent. Specifically, the wind velocity during dust storms appears to be more intermittent as compared with clean-air conditions. Among the multiple fields, the small-scale intermittency is strongest for PM10 dust concentration, moderate for electric fields and weakest for wind velocity. Furthermore, the anomalous scaling of multiple fields is well described by the hierarchical structure theory of turbulence. It is theoretically predicted that the wind velocity displays a one-dimensional filamentary structure, while the PM10 dust concentration and electric fields display two-dimensional sheet-like structures. Finally, after removing the coherent components of the observed time series by the proposed wavelet conditioning statistics, Kolmogorov linear scaling is recovered for the multiple fields, suggesting that small-scale multifield intermittency is caused by the presence of small-scale coherent structures.

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“…It is shown that the effect of cloth not only enhances the average value of instantaneous wind speed, but also causes the probability of strong wind to increase in the distribution of instantaneous wind speed. While depending on the fluttering mode of the cloth, the quasiconvective turbulence has coherent structures as observed in convective ABLs (Liu and Zheng, 2021). As our main interest is how convective eddies affects aeolian particle entrainment, we did not study the intrinsic mechanisms of how cloth induces large eddies.…”

Section: Forced Perturbationmentioning

confidence: 99%

Impact of turbulence on aeolian particle entrainment: results from wind-tunnel experiments

Zhang

Shi

et al. 2022

Atmos. Chem. Phys.

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Abstract. We hypothesize that large eddies play a major role in the entrainment of aeolian particles. To test this, wind-tunnel experiments are carried out to measure the particle entrainment rate for various sizes and flow conditions. Wind-tunnel flows are usually neutrally stratified with no large eddies, which are typically seen in convective atmospheric boundary layers. Here, a novel technique is applied, by deploying a piece of randomly fluttering cloth, to generate large eddies similar to convective eddies, here referred to as quasi-convective turbulence. The characteristics of quasi-convective turbulence are analyzed with respect to neutral turbulence in the Monin–Obukhov similarity framework, and the probability distributions of surface shear stress are examined. We show that for a given mean flow speed and in comparison with neutral flow conditions, quasi-convective turbulence increases the surface shear stress and alters its probability distribution and hence substantially enhances the entrainment of sand and dust particles. Our hypothesis is thus confirmed by the wind-tunnel experiments. We also explain why large eddies are important to aeolian entrainment and transport.

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Large-scale structures of wall-bounded turbulence in single- and two-phase flows: advancing understanding of the atmospheric surface layer during sandstorms

Abstract: Graphical Abstract

Cited by 25 publications

References 164 publications

The effect of turbulent motions on particle spatial distribution in high-Reynolds-number particle-laden flows

The effect of turbulent motions on particle spatial distribution in high-Reynolds-number particle-laden flows

Multifield intermittency of dust storm turbulence in the atmospheric surface layer

Impact of turbulence on aeolian particle entrainment: results from wind-tunnel experiments

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