The fundamental mechanisms involved in the resuspension and deagglomeration of particles on a surface when other particles bombard the surface will be studied. Experiments will be made with monodispense, spherical particles and with agglomerates of these particles, as well as with polydisperse, nonspherical particles. Controlled parameters include size, particle shape, and surface material. Particle size distributions before and after impact will be measured with optical counters. The number and location of particles remaining on the impaction surface will be measured by scanning electron microscopy via automatic image analysis and fluorescent tracers. Thus, the elementary processes in particle collisions will be identified and parametized. Resuspension and deagglomeration are among the least understood but most important aerosol phenomena. The production of dust during the process of soil erosion is not well understood; the resuspension of radioactive or toxic chemicals from soil has resisted major efforts at modelling. Dust from coal and ore piles and dust generated during the handling of powdered materials are other important problems affected by this work. The accuracy of sampling devices used to measure aerosols will also be improved by results of this work. The basic understanding provided by this project will advance the theory and control of these and other important engineering problems.
