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Measurement of the Influence of Directed Particle motion on the turbulent particle deposition velocity by means of laser‐doppler anemometry

 

作者: Werner Holländer,   Gerhard Pohlmann,  

 

期刊: Particle&Particle Systems Characterization  (WILEY Available online 1991)
卷期: Volume 8, issue 1‐4  

页码: 12-15

 

ISSN:0934-0866

 

年代: 1991

 

DOI:10.1002/ppsc.19910080104

 

出版商: WILEY‐VCH Verlag GmbH

 

数据来源: WILEY

 

摘要:

AbstractThe dry deposition of particles from the atmosphere is not well understood for reasons of surface variabilities and mutual interactions between surface and particles. However, even relatively simple influences of physical parameters have so far resisted successful parameterization, although some progress has been achieved. There is no general way to determine the relative contributions of stochastic turbulent and Brownian diffusion and directed motions (i. e. sedimentation) to the total deposition velocity since they contribute in a nonlinear manner to the total deposition velocity. The directed motion is an unknown function of atmospheric turbulence, the particle diffusion coefficientDpand the sum of all directed particle motions by thermophoresis, diffusiophoresis, photophoresis, electrophoresis, sedimentation etc. Practically nothing is known about the action of the first three forces and even the easily accessible electrophoresis has not been considered relevant for deposition of atmospheric particles. Because it is relatively easy to change an electric field with all other parameters kept constant and measure the absolute difference in total deposition velocity the following experimental Laser‐Doppler study was intended to show the feasibility of the field‐changing‐technique and the magnitude of the effects without quantitatively determining the electrical mobility distribution as a function of particle

 

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