Mechanisms of dust emission from different surfaces
,2, Zhenjiao Teng2, Ning Huang1
,2, Yaping Shao3
1Key Laboratory of Mechanics on Disaster and Environment in Western China, Lanzhou University, Lanzhou, China, 2School of Civil Engineering and Mechanics, Lanzhou University, Lanzhou, China, 3The Institute for Geophysics and Meteorology, University of Cologne, Cologne, Germany
Wind tunnel experiments over several typical surfaces are carried out to reveal the contribution and affecting factors for dust emission mechanisms. The effect of surface-renew, which could unfreeze supply-limiting of availability of surface material, is proposed and discussed. And also, several typical dust emission schemes are validated. Results show that the wind condition, the surface obstacle, the available free dust and the movement of surface particles have significant impact on dust emission, which could cause the variation of dust emission flux in orders of magnitude; aerodynamic entrainment of dust over natural and rough soil surface may run up to or exceed the amount caused by saltation bombardment in the first 1-3 minutes after the beginning of emission, but is hard to maintain without surface-renew process; in the process of dust emission, available free dust on the surface is the primary factor to suppress aerodynamic entrainment and also the saltation blasting efficiency. Results also indicate dust emission process may be primarily driven by aerodynamic entrainment and be limited by availability of surface material. Surface-renew process caused by saltation and creep should be an efficient way to unfreeze supply-limiting and restore surface available free dust. The existing typical dust emission scheme cannot predict emission flux accurately, because of the ignorance of aerodynamic entrainment effect and surface-renew process.