Effects of slope gradient and shape on climbing dunes： a wind tunnel experiment

doi:10.7522/j.issn.1000-694X.2020.00082

Journal of Desert Research ›› 2020, Vol. 40 ›› Issue (6): 118-126.DOI: 10.7522/j.issn.1000-694X.2020.00082

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Effects of slope gradient and shape on climbing dunes： a wind tunnel experiment

Xiaoxu Wang²(), Ping Yan³^,⁴(), Yong Wang², Miao Dong¹^,⁵, Yijiao Wang², Xiao Zhang²

^1.State Key Laboratory of Earth Surface Processes and Resource Ecology，Beijing Normal University，Beijing 100875，China
^2.MOE Engineering Research Center of Desertification and Blown-sand Control，Beijing Normal University，Beijing 100875，China
^3.Faculty of Geographical Science，Beijing Normal University，Beijing 100875，China
^4.State Key Laboratory of Earth Surface Processes and Resource Ecology Zhuhai Base，Beijing Normal University，Zhuhai 519087，Guangdong，China
^5.College of Geographic Science，Taiyuan Normal University，Taiyuan 030619，China

Received:2020-06-24 Revised:2020-07-24 Online:2020-12-09 Published:2020-12-09
Contact: Ping Yan

Abstract

Abstract:

The climbing dune is an important kind of topographically influenced dunes， and its formation is closely related to topography. In our wind tunnel experiment， the windward slope models of six slopes of 8°， 15°， 25°， 35°， 45°， 55°， and five shapes of windward slope， such as flat slope， concave shape， convex slope， concave-convex slope and stepped slope， were used to measure near-surface wind speeds under five wind speeds of 6， 8， 10， 12， 15， 18 m·s^-1， and the influence of slope gradient and s slope form of climbing dune were discussed. And with sand supply， those models were tested to simulate the sand accumulation on the slopes under the same condition of 8 m·s^-1wind speed. which is to verify the analysis results. The results show that：（1） The models have a certain blocking and lifting effect on the air flow near the surface， and the effect on the lower layer is greater than that on the upper layer；（2） The 25° and 35° are most favorable degrees for the formation of climbing dunes， followed by 8° and 15° models， 45° and 55° models are not easy to form climbing dunes；（3） Concave slope and stepped slope are most suitable for the formation of climbing dunes， followed by flat slope and concave-convex slope.

Key words: climbing dunes, slope gradients, slope forms, wind tunnel simulation experiment

CLC Number:

X169

Xiaoxu Wang, Ping Yan, Yong Wang, Miao Dong, Yijiao Wang, Xiao Zhang. Effects of slope gradient and shape on climbing dunes： a wind tunnel experiment[J]. Journal of Desert Research, 2020, 40(6): 118-126.

Figures/Tables 13

Fig.1 Schematic diagram of different models and location of measuring points on the slopes

Table 1 Model parameters of different slope gradients

模型参数	模型坡度/（°）
模型参数	8	15	25	35	45	55
高度/cm	4.5	8.3	13.5	18.4	22.5	26
长度/cm	32	31	29	26	22.5	18.4

Fig.2 Experimental arrangement of wind speed measurement near the surface of model

Fig.3 Wind speed profiles of each measuring point of model windward slope with different slope gradient under 8 m·s-1 wind speed

Fig.4 Wind speed profiles of each measuring point of windward slope of different slope form models under 8 m·s-1 wind speed

Fig.5 Change rates of wind speed at each measuring point of windward slope with different slope gradient under 8 m·s-1 wind speed

Fig.6 Change rates of wind speed at each measuring point of windward slope with different slope gradient under 8 m·s-1 wind speed

Fig.7 Change rates of wind speed at each measuring point of model windward slope with different slope form under different wind speeds

Fig.8 Change rates of wind speed at each measuring point of windward slope with different slope form under 8 m·s-1 wind speed

Fig.9 Deposition forms over slopes with different slope gradient under 8 m·s-1 wind speed

Table 2 Statistics of deposition morphology of windward slopes with different slope gradient under 8 m·s-1 wind speed

坡度	爬升坡长/cm	坡面面积/cm²	坡面沉积质量/kg
8°	12	324	0.30
15°	10	364	0.45
25°	15.6	560	1.03
35°	13.5	488	0.93
45°	0	0	0
55°	0	0	0

Fig.10 Deposition forms over slopes with different slope forms under 8 m·s1 wind speed

Table 3 Statistics of deposition morphology of windward slopes with different slope form types under 8 m·s-1 wind speed

坡度	爬升坡长/cm	坡面面积/cm²	坡面沉积质量/kg
平面坡	17	548	1.03
凹形坡	25	1092	1.84
凸形坡	11	380	0.73
凹凸组合坡	16	728	1.46
台阶形坡	*	920	2.13

References 24

1	Howard A H.Interaction of sand transport with topography with local winds in the northern Peruvian coastal desert ［C］//Barndorff-Nielsen O E.International Workshop on the Physics of Blown Sand. Aarhus，Denmark：University of Aarhus，1985，511-544.
2	Lancaster N，Tchakerian V P.Geomorphology and sediments of sand ramps in the Mojave desert ［J］.Geomorphology，1996，17（1）：151-165.
3	Cooke R U，Warren A，Goudie A，et al.Desert Geomorphology ［M］.Boca Raton，USA：CRC Press，1993.
4	钱广强，董治宝，罗万银，等.回涡沙丘的形态特征与表面物质组成［J］.中国沙漠，2012，32（3）：587-592.
5	张正偲，董治宝.风沙地貌形态动力学研究进展［J］.地球科学进展，2014，29（6）：734-747.
6	Evans.Falling and climbing sand dunes in the Cronese （"Cat"） Mountain Area，San Bernardino County，California［J］.Journal of Geology，1962，70（1）：107-113.
7	Chojnacki M，Moersch J E，Burr D M.Climbing and falling dunes in Valles Marineris，Mars［J］.Geophysical Research Letters，2010，37（8）：162-169.
8	杨军怀，董治宝，刘铮瑶，等.库鲁克沙漠风沙地貌与沙丘移动［J］.中国沙漠，2019，39（4）：1-8.
9	马玉凤，严平，宋阳，等.青海共和盆地多石在沟河道沙丘现代风水交互过程［J］.第四纪研究，2008（4）：695-701.
10	周娜，张春来，刘永刚.雅鲁藏布江米林宽谷段爬升沙丘粒度分异特征研究［J］.地理研究，2012，31（1）：82-94.
11	Tirsch D，Craddock R A，Platz T，et al.Spectral and petrologic analyses of basaltic sands in Ka’u Desert （Hawaii）-implications for the dark dunes on Mars［J］.Earth Surface Process and Landforms，2012，37（4）：434-448.
12	Blight G，Blight J，Blight G F.South Africa's mountain-climbing sand dunes mechanism of formation and present status ［J］.Civil Engineering，2013，21（7）：11.
13	White B R，Tsoar H.Slope effect on saltation over a climbing sand dune ［J］.Geomorphology，1998，22（2）：159-180.
14	杨转玲，钱广强，董治宝，等.库姆塔格沙漠北部三垄沙地区风成沉积物粒度特征［J］.中国沙漠，2016，36（3）：589-596.
15	董苗，严平，孟小楠，等.青藏高原爬坡沙丘地表沉积物特征分析：以柴达木盆地托拉海河为例［J］.水土保持学报，2018，32（4）：101-108.
16	Thomas D S G，Bateman M D，Mehrshahi D，et al.Development and environmental significance of an eolian sand ramp of last-glacial age，central Iran［J］.Quaternary Research，1997，48（2）：155-161.
17	李建国，屈建军，李芳，等.不同类型防沙堤流场的风洞实验模拟研究［J］.中国沙漠，2012，32（2）：291-299.
18	屈建军，刘贤万，雷加强，等.尼龙网栅栏防沙效应的风洞模拟实验［J］.中国沙漠，2001，21（3）：62-66.
19	罗万银，董治宝，钱广强，等.栅栏绕流减速效应风洞实验模拟［J］.中国沙漠，2010，30（1）：1-7.
20	Tsoar H.Wind tunnel modeling of echo and climbing dunes［M］//Brookfield M E， Ahlbrandt T S.Eolian Sediments and Processes. Amsterdam，Netherlands： Elsevier， 1983： 247-259.
21	魏振海，董治宝，胡光印，等.若尔盖盆地沙丘形成分布影响因素探讨［J］.中国沙漠，2009，29（6）：1035-1042.
22	李森，董光荣，申建友，等.雅鲁藏布江河谷风沙地貌形成机制与发育模式［J］.中国科学（D辑：地球科学），1999（1）：88-96.
23	哈斯，王贵勇.腾格里沙漠东南缘横向沙丘粒度变化及其与坡面形态的关系［J］.中国沙漠，1996，16（3）：8-13.
24	钱广强，董治宝，罗万银，等.不同坡度障碍物前气流场特征及其对回涡沙丘形成的影响［J］.中国科学：地球科学，2012，42（1）：34-41.

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Effects of slope gradient and shape on climbing dunes： a wind tunnel experiment

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