Dean-coupled inertial migration and transient focusing of particles in a curved microscale pipe flow

Abstract

The Dean-coupled inertial migration of neutrally buoyant spherical particles that are suspended in a curved microscale pipe flow was experimentally investigated in the range of and . The three-dimensional positions of the particles were measured by using digital holographic microscopy. The diameter of the microtube was 350 mu m, and the ratios of the tube diameter (D) to the particle diameter (d) were D/d = 12, 23, 35, and 50. Over a critical value of the Focusing number (F (C)), the particles were initially tubular-pinched at the entrance of the curved region. The detailed structures of the Segr,-Silberberg annulus as well as its deformation attributed to secondary flow were analyzed. Diverse agglomeration patterns of particles corresponding to the various flow conditions were observed. The optimal conditions that induced the particles to focus at a certain lateral position were determined.