Investigation on very large scale motions(VLSMs) and their influence in a dust storm  

作　　者：ZHENG XiaoJing ZHANG JingHong WANG GuoHua LIU HongYou ZHU Wei 

机构地区：[1]Key laboratory of Mechanics on Western Disasters and Environment(Ministry of Education),Lanzhou University [2]School of Civil Engineering and Mechanics,Lanzhou University

出　　处：《Science China(Physics,Mechanics & Astronomy)》2013年第2期306-314,共9页中国科学：物理学、力学、天文学（英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant Nos. 11232006,11121202,10972164,40830103,and 11072097);the State Key Dvelopment Program for Basic Research of China (Grant No. 2009CB421304)

摘　　要：Based on the real-time synchronous measurements of the wind velocity,temperature,the PM10 concentration at 16 m and 47 m during a dust storm event,in which Reynolds number Re exceeds 6×106,this study reveals the existence of the very large scale motions(VLSMs) during the stable stage both in the stream velocity and the temperature field at the two heights,whose streamwise scales reach up to 10 times the thickness of the boundary layer.The streamwise velocity and the PM10 concentration display a similar frequency corresponding to the peaks of their energy spectra,which implies that the VLSMs of streamwise flow have a significant role in dust transportation.In contrast,the salient deviations of the PM10 concentration at 47 m from the Gaussian distribution are revealed,which means that 47 m is not in the dust transportation layer,but is a region where the dust transportation layer and the outer flow intersect each other.Analysis demonstrates that the energy spectra of the PM10 concentrations at 16 m and 47 m display the "-1" scaling law feature,which has the same frequency range(0.001-0.1 Hz) as that of the wind velocity.This provides a new paradigm for the existence of the self-similarity scaling region in turbulent flow.Based on the real-time synchronous measurements of the wind velocity, temperature, the PM10 concentration at 16 m and 47 m during a dust storm event, in which Reynolds number Re exceeds 6×10^6, this study reveals the existence of the very large scale motions （VLSMs） during the stable stage both in the stream velocity and the temperature field at the two heights, whose streamwise scales reach up to 10 times the thickness of the boundary layer. The streamwise velocity and the PM10 concentration display a similar frequency corresponding to the peaks of their energy spectra, which implies that the VLSMs of streamwise flow have a significant role in dust transportation. In contrast, the salient deviations of the PM10 concentration at 47 m from the Gaussian distribution are revealed, which means that 47 m is not in the dust transportation layer, but is a region where the dust transportation layer and the outer flow intersect each other. Analysis demonstrates that the energy spectra of the PM 10 concentrations at 16 m and 47 m display the ＂-1＂ scaling law feature, which has the same frequency range （0.001-0.1 Hz） as that of the wind velocity. This provides a new paradigm for the existence of the self-similarity scaling region in turbulent flow.

关 键 词：high-Reynolds turbulence dust storm very large scale motions power spectrum field observation 

分 类 号：P445.4[天文地球—大气科学及气象学]