Fetch effect on the developmental process of aeolian sand transport in a wind tunnel

作     者：CHEN Zongyan XIAO Fengjun DONG Zhibao CHEN Zongyan;XIAO Fengjun;DONG Zhibao

作者机构：School of Geography and TourismShaanxi Normal UniversityXi'an 710119China College of Geographic ScienceQinghai Normal UniversityXining 810008China 

出 版 物：《Journal of Arid Land》 (干旱区科学（英文版）)

年 卷 期：2020年第12卷第3期

页      面：436-446页

核心收录：

学科分类：09[农学] 0903[农学-农业资源与环境] 

基　　金：supported by the National Natural Science Foundation of China (41601002, 41871011) the China Postdoctoral Science Foundation (2017M623115) the Science Foundation of Shaanxi Province (2018JQ4010) the Fundamental Research Funds for the Central Universities (GK201903077) 

主　　题：fetch length mass flux profile grain size distribution sand transport wind tunnel experiment 

摘      要：As the sand mass flux increases from zero at the leading edge of a saltating surface to the equilibrium mass flux at the critical fetch length,the wind flow is modified and then the relative contribution of aerodynamic and bombardment entrainment is *** the end the velocity,trajectory and mass flux profile will vary *** how the transportation of different sand size groups varies with fetch distance is still *** tunnel experiments were conducted to investigate the fetch effect on mass flux and its distribution with height of the total sand and each size group in *** mass flux was measured at six fetch length locations(0.5,1.2,1.9,2.6,3.4 and 4.1 m)and at three free-stream wind velocities(8.8,12.2 and 14.5 m/s).The results reveal that the total mass flux and the mass flux of each size group with height can be expressed by q=aexp(–bh),where q is the sand mass flux at height h,and a and b are regression *** coefficient b represents the relative decay *** the relative decay rates of total mass flux and each size group are independent of fetch length after a quick decay over a short *** is much shorter than that of mass *** equilibrium of the relative decay rate cannot be regarded as an equilibrium mass flux profile for aeolian sand *** mass fluxes of 176.0,209.3 and 148.0μm size groups increase more quickly than that of other size groups,which indicates strong size-selection of grains exists along the fetch *** maximal size group in mass flux(176.0μm)is smaller than the maximal size group of the bed grains(209.3μm).The relative contribution of each size group to the total mass flux is not monotonically decreasing with grain size due to the lift-off of some small grains being reduced due to the protection by large *** results indicate that there are complex interactions among different size groups in the developmental process of aeolian sand transport and more attention sh