FIGURE 7.

Equilibrium positions of spherical particles in flow depend on Reynolds number, particle stiffness, and conduit geometry. We adopt the following color convention in this paper: orange for deformable particles, red for stiff particles. At high Re (left hand side of the figure), stiff particles migrate away from the wall and away from the centerline, to a position approximately 40% away from the wall towards the center. The higher the Re, the closer to the wall is the equilibrium location. Round channels exhibit a ring of stiff particles at equidistance from the center, and rectangular geometries exhibit four distinct equilibrium positions in which stiff particles form trains.¹⁸,³⁹ Deformable particles on the other hand, migrate towards the center. At low Re (right hand side of the figure), both stiff and deformable particles migrate towards the center of the channel.