Vertical Mass Flux Profiles of Different Grain Size Groups in Aeolian Sand Transport
Received date: 2007-06-15
Revised date: 2007-08-06
Online published: 2007-11-25
Supported by
National Natural Science Foundation of China, No.49625101
This paper presented the vertical mass flux profiles of different grain size groups in aeolian sand transport, which is the hot issue of non-uniform sand transport research but is rarely studied recently. The sand samples of vertical mass flux were further investigated using a particle size analyzer that were measured in a wind tunnel experiment conducting with non-uniform sands and five different stream velocities. Results show that the vertical mass flux profiles of coarse sand groups are similar to that of all sands measured in the wind tunnel, exhibiting an exponential decay distribution with a positive deviation occurring in the near-bed region; however, the vertical mass flux profiles of fine sand groups decayed exponentially in the whole height. Based on the results above, this study simulated the vertical mass flux profiles of different grain size groups in terms of equilibrium saltation theory. It is revealed that in the non-uniform sand transport, the launch speed and angle distributions of coarse sand are exponential function; the launch speed of fine sand is exponential function but the launch angle of it is Gaussian function. The mean sand launch speed occur between 0.4u* and 2.2u*, decaying with the increase of wind speed (u*) and grain size.
FENG Dajun, NI Jinren, LI Zhenshan . Vertical Mass Flux Profiles of Different Grain Size Groups in Aeolian Sand Transport[J]. Acta Geographica Sinica, 2007 , 62(11) : 1194 -1203 . DOI: 10.11821/xb200711008
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