The dynamics of particles with translation–rotational coupling in the stokes flow regime

Most naturally and industrially generated solid particles are irregular in shape. One type of particle commonly encountered can be identified as flakes and their aggregates. This class of particles exhibits translation-rotational coupling. Based on the principle of similarity, we have conducted an experimental investigation of the dynamics of flake-type particles, employing model particles settling in an oil tank. These model particles are about 1–2 cm in size. The particle Reynolds number is kept under 0.02 to simulate the motion of the flaky aerosols. By introducing factors representing the effects of configuration (e.g., finite thickness and rod diameter) and interaction, shape factors for the composite particles can be determined from the constituent disks. The translational configuration factor λ_t is found to depend mainly on the thickness-to-diameter ratio lls_s/d_s and to satisfy λ_t = A + B(1_s/d_s)^0.14. Furthermore, the ratio of the rotational and coupling configuration factors generally increases with the length of the rod connecting the disks. The wall effect depends linearly on the ratio d_s/D_T (where D_T is the tank diameter) for translational motion but is insignificant for rotational motion.