野外近地表风沙流脉动特征分析
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摘要
基于风沙流实时测量系统对流沙地表的输沙强度以及不同高度风速进行实时测量所获得的数据,分析野外实际风场中的风沙流脉动特征。结果表明:沙粒的存在削弱平均流场,但对风速的高阶统计矩和分布形式影响不大,不同高度、不同来流平均风速条件下,风沙流中风速仍近似符合高斯分布;瞬时输沙强度服从指数分布,滞后风速约1s,脉动强烈;30min输沙强度平均值和脉动标准差均随平均风速的增大而呈幂函数增加,但随风速脉动强度的变化呈先增大后减小的趋势。这意味着脉动风速对输沙率具有重要影响,需要在输沙率预测公式中予以考虑。
This paper analyzes the fluctuating characteristics of wind-blown sand flux on the basis of the data acquired from the real-time measurements of wind velocity and saltation intensity by the measurement system.The results show that sand saltation reduces the mean wind velocity,but it has little influence on higher order statistical moments and probability distribution of wind series.Wind velocity in drifting sand approximately accords with Gaussian distribution under different heights and different mean wind velocities.Instantaneous saltation intensity obeys exponent distribution and is roughly 1s late to the wind speed,and the fluctuation is fierce.As the average wind velocity increase,the average saltation wind-blown sand flux in 30 min intervals and its fluctuation augment in the form of power function.But with the change of the wind fluctuation,the average saltation wind-blown sand flux augments at first,then minishes.It indicates that the fluctuation of wind velocity is essential to saltation wind-blown sand flux and should be taken into consideration in prediction formula of transport rate.
This paper analyzes the fluctuating characteristics of wind-blown sand flux on the basis of the data acquired from the real-time measurements of wind velocity and saltation intensity by the measurement system.The results show that sand saltation reduces the mean wind velocity,but it has little influence on higher order statistical moments and probability distribution of wind series.Wind velocity in drifting sand approximately accords with Gaussian distribution under different heights and different mean wind velocities.Instantaneous saltation intensity obeys exponent distribution and is roughly 1s late to the wind speed,and the fluctuation is fierce.As the average wind velocity increase,the average saltation wind-blown sand flux in 30 min intervals and its fluctuation augment in the form of power function.But with the change of the wind fluctuation,the average saltation wind-blown sand flux augments at first,then minishes.It indicates that the fluctuation of wind velocity is essential to saltation wind-blown sand flux and should be taken into consideration in prediction formula of transport rate.
引文
[1]Bagnold R A.The Physics of Blown Sand and Desert Dune[M].London,UK:Methuen,1941.
[2]Ma G S,Zheng X J.The fluctuation property of blown sand particles and the wind-sand flow evolution studied by numerical method[J].The European Physical Journal E,2011,34(5):54.
[3]Zheng X J.Mechanics of Wind-blown Sand Movement[M].Berlin,Germany:Springer,2009.
[4]Butterfield G R.Grain transport rates in steady and unsteady turbulent airflows[J].Acta Mechanica,1991,1(Sup):97-122.
[5]杨斌,王元,刘江,等.风沙流中沙粒相浓度的高频测量[J].实验流体力学,2010,24(5):47-50.
[6]Wyngaard J C.Atmospheric turbulence[J].Annual Review of Fluid Mechanics,1992,24:205-234.
[7]Kaimal J C,Wyngaard J C,Izumi Y,et al.Spectral characteristics of surface-layer turbulence[J].Quarterly Journal of the Royal Meteorological Society,1972,98:563-589.
[8]郑晓静,张静红.2010年3月19日沙尘暴期间甘肃民勤地区近地表的湍流性质[J].科学通报,2010,55(22):2235-2240.
[9]Stout J E,Zobeck T M.Intermittent saltation[J].Sedimentology,1997,44:959-972.
[10]Barchyn T E,Hugenholtz C H.Comparison of four methods to calculate aeolian sediment transport threshold from field data:implications for transport prediction and discussion[J].Geomorphology,2011,129:190-203.
[11]Bass A C W.The Formation and Behavior of Aeolian Streamers[D].Los Angeles,USA:University of Southern California,2003.
[12]Butterfield G R.Sand transport response to fluctuating wind velocity[C]//Clifford N J,Trench J R,Hardisty J.Turbulent:Perspectives on Flow and Sediment Transport.New York,USA:John Wiley&Sons,1993:305-335.
[13]Butterfield G R.Transitional behaviour of saltation:wind tunnel observations of unsteady winds[J].Journal of Arid Environments,1998,39:377-394.
[14]Srenssen M.On the effect of time variability of the wind on rates of aeolian sand transport[J].Aarhus Geoscience,1997,7:73-77.
[15]Jackson W T,McCloskey J.Preliminary results from a field investigation of aeolian sand transport using high resolution wind and transport measurements[J].Geophysical Research Letter,1997,24(2):163-166.
[16]Davidson-Arnott R G D,Bauer B O,Walker I J,et al.Instantaneous and mean aeolian sediment transport rate on beaches:an intercomparison of measurements from two sensor types[J].Journal of Coastal Research,2009,SI 56:297-301.
[17]Davidson-Arnott R G D,Quarrie K M,Troels A.The effect of wind gusts,moisture content and fetch length on sand transport on a beach[J].Geomorphology,2005,68:115-129.
[18]常兆丰,赵明.民勤荒漠生态研究[M].兰州:甘肃科学技术出版社,2006.
[19]Lumley J L,Panofsky H A.The Structure of Atmospheric Turbulence[M].New York,USA:Wiley,1964.
[20]Chu C R,Parlange M B,KatulG G,et al.Probability density functions of turbulent velocity and temperature in the atmospheric surface layer[J].Water Resources Research,1996,32(6):1681-1688.
[21]李振山,倪晋仁.风沙流中风速脉动的实验测量[J].应用基础与工程科学学报,2003,11(4):353-360.
[22]Sterk G,Jacobs A F G,Van Boxel J H.The effect of turbulent flow structures on saltation sand transport in the atmospheric boundary layer[J].Earth Surface Processes and Landforms,1998,10:877-887.
[23]Pfeifer S,Schnfeldt H J.The response of saltation to wind speed fluctuations[J].Earth Surface Processes and Landforms,2012,37(10):1056-1064.
[24]杨东亮,王雪芹,胡永锋,等.风沙流输沙通量垂向分布研究——以塔克拉玛干沙漠南缘流沙地表风沙流观测为例[J].中国沙漠,2012,32(3):631-639.
[25]武建军,罗生虎,闫光虎,等.脉动风场下风沙流结构的数值模拟.中国沙漠,2011,31(3):602-606.
[26]彭晓庆,王萍.风速正弦变化下的非平稳跃移风沙流模拟[J].中国沙漠,2011,31(3):588-592.
[27]张克存,屈建军,董治宝,等.风沙流中风速脉动对输沙量的影响[J].中国沙漠,2006,26(3):336-340.
[2]Ma G S,Zheng X J.The fluctuation property of blown sand particles and the wind-sand flow evolution studied by numerical method[J].The European Physical Journal E,2011,34(5):54.
[3]Zheng X J.Mechanics of Wind-blown Sand Movement[M].Berlin,Germany:Springer,2009.
[4]Butterfield G R.Grain transport rates in steady and unsteady turbulent airflows[J].Acta Mechanica,1991,1(Sup):97-122.
[5]杨斌,王元,刘江,等.风沙流中沙粒相浓度的高频测量[J].实验流体力学,2010,24(5):47-50.
[6]Wyngaard J C.Atmospheric turbulence[J].Annual Review of Fluid Mechanics,1992,24:205-234.
[7]Kaimal J C,Wyngaard J C,Izumi Y,et al.Spectral characteristics of surface-layer turbulence[J].Quarterly Journal of the Royal Meteorological Society,1972,98:563-589.
[8]郑晓静,张静红.2010年3月19日沙尘暴期间甘肃民勤地区近地表的湍流性质[J].科学通报,2010,55(22):2235-2240.
[9]Stout J E,Zobeck T M.Intermittent saltation[J].Sedimentology,1997,44:959-972.
[10]Barchyn T E,Hugenholtz C H.Comparison of four methods to calculate aeolian sediment transport threshold from field data:implications for transport prediction and discussion[J].Geomorphology,2011,129:190-203.
[11]Bass A C W.The Formation and Behavior of Aeolian Streamers[D].Los Angeles,USA:University of Southern California,2003.
[12]Butterfield G R.Sand transport response to fluctuating wind velocity[C]//Clifford N J,Trench J R,Hardisty J.Turbulent:Perspectives on Flow and Sediment Transport.New York,USA:John Wiley&Sons,1993:305-335.
[13]Butterfield G R.Transitional behaviour of saltation:wind tunnel observations of unsteady winds[J].Journal of Arid Environments,1998,39:377-394.
[14]Srenssen M.On the effect of time variability of the wind on rates of aeolian sand transport[J].Aarhus Geoscience,1997,7:73-77.
[15]Jackson W T,McCloskey J.Preliminary results from a field investigation of aeolian sand transport using high resolution wind and transport measurements[J].Geophysical Research Letter,1997,24(2):163-166.
[16]Davidson-Arnott R G D,Bauer B O,Walker I J,et al.Instantaneous and mean aeolian sediment transport rate on beaches:an intercomparison of measurements from two sensor types[J].Journal of Coastal Research,2009,SI 56:297-301.
[17]Davidson-Arnott R G D,Quarrie K M,Troels A.The effect of wind gusts,moisture content and fetch length on sand transport on a beach[J].Geomorphology,2005,68:115-129.
[18]常兆丰,赵明.民勤荒漠生态研究[M].兰州:甘肃科学技术出版社,2006.
[19]Lumley J L,Panofsky H A.The Structure of Atmospheric Turbulence[M].New York,USA:Wiley,1964.
[20]Chu C R,Parlange M B,KatulG G,et al.Probability density functions of turbulent velocity and temperature in the atmospheric surface layer[J].Water Resources Research,1996,32(6):1681-1688.
[21]李振山,倪晋仁.风沙流中风速脉动的实验测量[J].应用基础与工程科学学报,2003,11(4):353-360.
[22]Sterk G,Jacobs A F G,Van Boxel J H.The effect of turbulent flow structures on saltation sand transport in the atmospheric boundary layer[J].Earth Surface Processes and Landforms,1998,10:877-887.
[23]Pfeifer S,Schnfeldt H J.The response of saltation to wind speed fluctuations[J].Earth Surface Processes and Landforms,2012,37(10):1056-1064.
[24]杨东亮,王雪芹,胡永锋,等.风沙流输沙通量垂向分布研究——以塔克拉玛干沙漠南缘流沙地表风沙流观测为例[J].中国沙漠,2012,32(3):631-639.
[25]武建军,罗生虎,闫光虎,等.脉动风场下风沙流结构的数值模拟.中国沙漠,2011,31(3):602-606.
[26]彭晓庆,王萍.风速正弦变化下的非平稳跃移风沙流模拟[J].中国沙漠,2011,31(3):588-592.
[27]张克存,屈建军,董治宝,等.风沙流中风速脉动对输沙量的影响[J].中国沙漠,2006,26(3):336-340.
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