From dome dune to barchan dune: Airflow structure changes measured with particle image velocimetry in a wind tunnel

Qian, Guangqiang; Yang, Zhuanling; Tian, Min; Dong, Zhibao; Liang, Aimin; Xing, Xuegang

doi:10.1016/j.geomorph.2021.107681

Cited by 11 publications

(11 citation statements)

References 30 publications

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“…Qian et al. (2021) have recently shown such a morphological transition in the field, and complemented these observations with wind tunnel measurements over solid model replicas, but their work involved no measurements of sediment transport. Therefore, measurements of streamwise profiles of sediment flux over several protodunes throughout the developmental stages would help considerably to close this knowledge gap.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, filling in the gap between the final protodune stage considered herein, CrestDown, and the presumed eventual mature dune morphology (the "Mature" case herein), is similarly dependent on field data. Qian et al (2021) have recently shown such a morphological transition in the field, and complemented these observations with wind tunnel measurements over solid model replicas, but their work involved no measurements of sediment transport. Therefore, measurements of streamwise profiles of sediment flux over several protodunes throughout the developmental stages would help considerably to close this knowledge gap.…”

Section: Remaining Questionsmentioning

confidence: 99%

“…Measurements of flow perturbation over aeolian and subaqueous dunes in both experiments and field environments have revealed the influence of topographic steering by dune morphology on both mean and turbulent flow (Baddock et al., 2011; Bristow et al., 2018, 2020, 2021; Maddux, McLean, & Nelson, 2003; Maddux, Nelson, & McClean, 2003; McKenna Neuman et al., 1997; Neuman et al., 2000; Walker & Nickling, 2002; Wiggs & Weaver, 2012), and have promoted an understanding of how these forced flow patterns may influence dune migration and growth by driving patterns of sand flux (Bennett & Best, 1995; Best, 2005; Claudin et al., 2013; Weaver and Wiggs, 2011). Studies on the dynamics of mature aeolian dunes have encouraged interest in the development of early‐stage dunes, with research examining the controls on the growth of nascent aeolian protodunes into mature dune forms (Baddock et al., 2018; Delorme et al., 2020; Elbelrhiti, 2012; Gadal et al., 2020; Nield, 2011; Nield et al., 2011; Qian et al 2021…”

Section: Introductionmentioning

confidence: 99%

“…For example, Claudin et al (2013) measured airflow over a 2 m high, low-angle dune in Morocco using traditional cup anemometers. Qian et al (2021) reported morphological measurements using a kinematic GPS system for a dome dune in its transition first to a "protobarchan" and then a mature barchan dune, all of which were on the order of 1 m in height. These measurements were supplemented by wind tunnel measurements of flow over downscaled models, but the study lacked measurements of sediment transport.…”

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confidence: 99%

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Topographic perturbation of turbulent boundary layers by low‐angle, early‐stage aeolian dunes

Bristow

Best

Wiggs

et al. 2022

Earth Surf Processes Landf

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Decimeter-scale early-stage aeolian bedforms represent topographic features that differ notably from their mature dune counterparts, with nascent forms exhibiting more gently sloping lee sides and a reverse asymmetry in their flow-parallel bed profile compared to mature dunes. Flow associated with the development of these "protodunes," wherein the crest gradually shifts downstream towards its mature state, was investigated by studying the perturbation of the turbulent boundary layer over a succession of representative bedforms. Rigid, three-dimensional models were studied in a refractive-index-matched experimental flume that enabled near-surface quantification of mean velocities and Reynolds stresses using particle-image velocimetry in wall-normal and wall-parallel measurement planes. Data indicate strong, topographically induced flow perturbations over the protodunes, to a similar relative degree to that found over mature dunes, despite their low-angled slopes.The shape of the crest is found to be an important factor in the development of flow perturbations, and only in the case with the flattest crest was maximal speed-up of flow, and reduction in turbulent stresses, found to occur upstream of the crest. Investigation of the log-linearity of the boundary layer profile over the stoss sides showed that, although the profile is strongly perturbed, a log-linear region exists, but is shifted vertically. A streamwise trend in friction velocity is thus present, showing a behavior similar to the trends in mean velocity. Analysis of the growth of the internal boundary layer on the dune stoss sides, beginning at the toe region, reveals a similar development for all dune shapes, despite clear differences in mean velocity and turbulent stress perturbations in their toe regions. The data presented herein provide the first documentation of flow over morphologies broadly characteristic of subtle, low-angle, aeolian protodunes, and indicate key areas where further study is required to yield a more complete quantitative understanding of flow-form-transport couplings that govern their morphodynamics.

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Section: Discussionmentioning

confidence: 99%

Section: Remaining Questionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Topographic perturbation of turbulent boundary layers by low‐angle, early‐stage aeolian dunes

Bristow

Best

Wiggs

et al. 2022

Earth Surf Processes Landf

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“…It is now assumed that wind ripples are formed by air-particle movement interactions, dunes are developed through bedform-airflow feedback, and megadunes are possibly controlled by the thickness of atmospheric boundary layer. However, our understanding regarding the mechanism of aeolian bedforms is limited to selected dune types, typically barchan and linear dunes (Rozier et al, 2019;Qian et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Advancement of Megadunes and its Implications in the Badain Jaran Sand Sea

2022

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The tallest megadunes on the Earth are developed in China’s Badain Jaran Sand Sea, as a result of which a prolonged curiosity exists with regards to the existence and migration of such large dunes. However, our present understanding of movement of aeolian bedforms is largely limited to dunes with height ranging from several to several tens of meters. Difficulties in understanding the movement of megadunes predominantly exists in the monitoring methods. This study presents the evidence of the megadune advancement and its rate in the Badain Jaran Sand Sea, estimated by optically stimulated luminescence (OSL) dating of sediments on the slipfaces of several megadunes. It is suggested that megadunes experience similar advancement as the commonly observed sand dunes; the rate of advancement of megadunes fits the rate-height relationship. The rate of advancement varies linearly with the reciprocal of megadune height, which has been confirmed for dunes, extending the advancement rate-height relationship to a previously blind range of dune size. In addition, the advancement rate of megadunes exhibits far-reaching implications for megadune formation. In combination with other morphometric evidences, it exemplifies the assumption that the development of megadunes is predominantly controlled by wind rather than other factors such as the underlying relief and ground water, as accepted by most researchers.

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UAV‐SfM‐based field quantification of barchan dune celerity and morphodynamics in Gonghe Basin

Shao,

Luo,

Che

et al. 2024

Earth Surf Processes Landf

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Barchan dunes do not often coexist with grasslands. However, in Gonghe Basin, north‐eastern part in Qinghai‐Tibetan Plateau (QTP), China, many barchan dunes are distributed on the grassland at high altitude. Identifying celerity and morphodynamics of barchan dunes and exploring the interaction between barchans and grassland landscape can help us better understand aeolian system sand mitigate damages. In this work, we tracked dune celerity and observed three‐dimensional changes of symmetrical and asymmetrical barchan dunes in Ertala based on high‐resolution UAV‐SfM reconstruction in short‐term monitoring and discussed the factors influencing dune celerity and deformation at high altitude. The results revealed that the barchan dunes are highly mobile with an average celerity of 0.85 m/M for the whole study area. Based on observations of dune morphology and dynamics, we found the following: (1) The dune deformation degree in a short time is not large but is widespread, especially in the elongated arm of asymmetric dune. The deformation of symmetric dune is symmetrical, whereas that of dune with extended horn is asymmetrical; (2) the sand supply, vegetation and airflow at low air density all influence the celerity and deformation degree in the development of barchan dunes; (3) the asymmetric airflow and sediment supply are important cause of dune asymmetry. The above results help us understand the deformation of barchan dune from the three‐dimensional, especially the difference reflected by the symmetry of barchan dune at high altitude.

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From dome dune to barchan dune: Airflow structure changes measured with particle image velocimetry in a wind tunnel

Cited by 11 publications

References 30 publications

Topographic perturbation of turbulent boundary layers by low‐angle, early‐stage aeolian dunes

Topographic perturbation of turbulent boundary layers by low‐angle, early‐stage aeolian dunes

Advancement of Megadunes and its Implications in the Badain Jaran Sand Sea

UAV‐SfM‐based field quantification of barchan dune celerity and morphodynamics in Gonghe Basin

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