| 砾石床面的空气动力学粗糙度 |
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| 引用本文： | 刘小平,董治宝.砾石床面的空气动力学粗糙度[J].中国沙漠,2003,23(1):38-45. |
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| 作者姓名： | 刘小平 董治宝 |
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| 作者单位： | 中国科学院 寒区旱区环境与工程研究所风沙物理与沙漠环境实验室, 甘肃 兰州 730000 |
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| 基金项目： | 中国科学院"百人计划"项目,国家自然科学基金项目(批准号:40001005)资助 |
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| 摘 要： | 通过砾石床面的空气动力学粗糙度(Z0)的风洞实验研究,结果表明,砾石床面的空气动力学粗糙度(Z0)与砾石粒径、砾石覆盖度和自由风速有关,Bagnold的1/30定律和其它有关空气动力学粗糙度与粗糙元高度的固定比例对砾石床面都不适用。在各种一定砾石覆盖度条件下,砾石床面的Z0随自由风速的增加而呈指数衰减。在各种一定自由风速条件下,Z0随砾石覆盖度C的变化遵循二次曲线:Z0=F1+F2C+F3C1.5+F4C2,砾石覆盖度为40%~75%时,Z0达到最大值。建立了包含自由风速和砾石覆盖度两个因子的Z0的双因子综合模型。
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| 关 键 词： | 空气动力学粗糙度 砾石覆盖度 预测模型 |
| 文章编号： | 1000-694X(2003)01-0038-08 |
| 收稿时间： | 2001-08-06 |
| 修稿时间： | 2001年8月6日 |
Aerodynamic Roughness of Gravel Beds |
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| LIU Xiao-ping,DONG Zhi-bao.Aerodynamic Roughness of Gravel Beds[J].Journal of Desert Research,2003,23(1):38-45. |
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| Authors: | LIU Xiao-ping DONG Zhi-bao |
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| Institution: | Laboratory of Blown Sand Physics and Desert Environments, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China |
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| Abstract: | The nature of interactions between surface winds and gravel beds that can be characterized by aerodynamic roughness length has important implications for sediment mobilization,transport and sedimentation.We report here the wind tunnel results of systematic tests of the aerodynamic roughness lengths of different gravel size and gravel coverage beds at various free-stream wind velocities.The aerodynamic roughness of gravel beds is a function of gravel size,gravel coverage and free-stream wind velocity.The 1/30 law proposed by Bagnold or simply assuming the aerodynamic roughness as fixed ratio of roughness element height in aeolian study is not hold true for gravel beds.Aerodynamic roughness of gravel beds decreases with free-stream wind velocity.The variation of aerodynamic roughness with gravel coverage can be expressed by quadric curves:Z0=F1+F2C+F3C1.5+F4C2,that bear the maximum aerodynamic roughness length at gravel coverage range from 40% to 75%,increasing with gravel size.The muti-variate models based on free-stream wind velocity and gravel coverage have been developed for predicting the aerodynamic roughness of different gravel-sized beds. |
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| Keywords: | aerodynamic roughness gravel coverage prediction model |
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