THE DYNAMICS OF PARTICLES

摘要: This chapter discusses the dynamics of particles. The study particles is essential for a proper understanding air cleaning and sampling apparatus in which one concerned with particle sizes from about 10 -8 to -3 m diameter. Aerodynamic properties vary considerably over this range. often remarkable persistence dust clouds still due fact that, small particle, resistance opposing its motion, even at very low velocity, equals gravitational force, so that after accelerating under gravity short distance, attains constant falling or terminal velocity. great differences velocities illustrate while it may be feasible remove 1 mm diameter simply by passing dust-laden through settling chamber, certainly not practical proposition submicron Even when projected high velocities, micron-sized are rapidly stopped resistance, their subsequent motion being almost solely movements. spherical, drag force same as sphere mass. In addition, orientation of, hence on, an irregular-shaped changes Reynolds number. As air-cleaning devices depend upon aerodynamic behavior particles, rather than on volume, equations derived spheres must modified take account shape.