On the Calculation of Aerodynamic Diameters of Fibers

This paper is restricted to the theoretical expressions for calculation of the aerodynamic diameters of fibers based on the viscous drag of prolate spheroids. The volume of the fibers is calculated either by the expression for a cylinder (Harris and Fraser, 1976) or the expression for a prolate spheroid (Khalik and Gonda, 1984). Perpendicular, parallel, or random orientations of the fibers with respect to the direction of motion are considered. The latter orientation can be expressed in two ways (Fuchs, 1964; Harris and Fraser, 1976). The recent experimental data of Prodi et al. (1982) appear to agree well with the theories that describe both the viscous drag and the volume in terms of prolate spheroids. The calculations suggest that the fibers are oriented randomly, or perpendicularly to the direction of the flow.