Turbulence-dust-electrostatics Interactions Within The Near-surface Region During Dust Storms

Dust storms are a unique type of particle two-phase flow with a strong electric field.Previous studies have mainly focused on the impact of the average electric field on dust transport in dust storms,with little attention paid to the effects of turbulent electric fields.This paper analyzes the interaction between the turbulent electric field near the ground and the vertical dust flux in dust storms based on a large amount of wind speed,dust concentration,and electric field data measured by the Qingtu Lake Observation Array（QLOA）of Lanzhou University from April to May 2021.The linear and quadratic interactions between turbulence,dust,and electric fields are explored.Specifically,the impact of turbulent electric fields on dust transport at different scales is analyzed based on the power spectra and coherence spectra calculated using the continuous wavelet transform（Morlet wavelet）.Furthermore,the linear and quadratic interactions are analyzed using the wavelet coherence and bicoherence spectra.The results show that the large-scale（wavenumber6）₁=0.002)turbulent electric field has the highest correlation with and contributes the most to the vertical dust flux,while its contribution is small at the turbulence integral scale.Secondly,in terms of linear interactions,it is found that there is good linear coupling between the streamwise wind speed,dust,and electric field at aroundf=10^-3,and the dust concentration and electric field strength have better linear coupling with the streamwise wind speed both in the frequency and time domain.Finally,in terms of quadratic interactions,the frequency scale of the quadratic coupling phenomenon of the streamwise wind speed is aroundf=10^-3,while the dust concentration and electric field both exhibit quadratic coupling phenomena at frequencies off=10^-3 andf=10^-2.These results further advance our understanding of the dust transport process in dust storms.