On the inertial separation of nonspherical aerosol particles from laminar flows. I. The cylindrical case
The inertial separation of cylindrical particles from laminar flows was studied theoretically and experimentally. The calculational method introduced was based on the simultaneous solution of the equations of particle translation and rotation, in which the expression for the operating fluid-dynamic force and torque was obtained from slender body theory. The collecting obstacles chosen for the exemplification of the method were a long circular cylinder and a nuclepore hole. The necessary undisturbed flow fields in the vicinity of these obstacles were derived by a numerical solution of the full Navier-Stokes equation. Particle trajectories, specifying location and orientation, were generated with the aid of a computer. The experiments consisted of the determination of the motion of macrocylinders within a liquid flow channel near models of the above two obstacles. Both particle location and orientation could be ascertained by video photography from two directions of sight, an elaborate s ubsequent recording, and data processing. A comparison of theoretical and experimental trajectories for identical conditions was made, whereby a satisfactory agreement was observed. Consequently, trajectories of aerosol particles were calculated, and efficiencies of collision with a cylindrical fiber and in a nuclepore system were found. In general, the motion of particles in this study was characterized by a pronounced rotation, a tendency of alignment on a time basis along the flow lines orientation.