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Gas and particle motion.
Aerosol measurement: principles, techniques, and applications, second edition. Baron PA, Willeke K, eds. New York: John Wiley and Sons, Inc., 2001 Sep; :61-82
Aerosols consist of two components: a gas or gas mixture, most commonly air; and the particles suspended in it. The behavior of the particles within the aerosol depends to a large extent on the motion and intrinsic properties of the suspending gas. Submicrometer-sized particles, especially those less than 0.1 um diameter, are affected by the motion of individual gas molecules (the free molecular regime). Thus, the kinetic theory of gases is useful in understanding the behavior of these particles. Larger particles can be treated as being submersed in a continuous gaseous medium or, more broadly, a fluid (the continuum regime). The tools of gas or fluid dynamics are more useful for this size range. Intermediate-sized particles usually can be treated by adjustment of equations from the continuum regime. The intermediate range is termed the transition or slip regime. Whether considering a molecular ensemble or a continuous fluid, the motion of the gas will largely dictate the behavior of the suspended particles. In this chapter, concepts and parameters that affect gas and particle motion are discussed and quantified as migration and deposition parameters in specific force fields.
Gases; Aerosols; Gas-mixtures; Fluids; Environmental-exposure; Environmental-factors
Aerosol measurement: principles, techniques, and applications, second edition
Page last reviewed: April 12, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division