| 沙漠与沙漠化 |
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| Wind Tunnel Simulation on Flow Reattachment on Lee of Transverse Dunes |
| QIAN Guang qiang; DONG Zhi bao; LUO Wan yin; WANG Hong tao |
| Key Laboratory of Desert and Desertification, Chinese Academy of Sciences; Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China |
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Abstract Secondary airflow plays an important role in dune initiation and form maintenance. Airflow speeding\|up over the stoss slope and separating at the crest were described and mentioned widely in the dune dynamic researches. Secondary airflow in the lee side of dune, especially the flow separation (i.e. reversal vortex) and the reattachment, has an important significance in shaping the lee slope and in controlling the dune spacing and alignment. In this paper, a series experiments were conducted in a wind tunnel using Particle Image Velocimetry (PIV) to study the factors in controlling flow reattachment in the lee side of transverse dunes. The results showed that the flow reattachment distance in the lee side of various dune models are ranged from 4\^8H to 10\^8H (H is dune height) depending on different stoss slopes, the maximum of flow reattachment distance was found in the lee side of the transverse dune with a 15° stoss slope angle. The stoss slope angles have more influence in controlling the flow reattachment than free stream velocities. Finally, the sedimentary significance of the flow separation and the reattachment was discussed in detail.
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Received: 01 November 2006
Published: 20 January 2008
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2008, Vol. 28 
