Abstract: The flows of macromolecules in micro- and nanoscale channels are of paramount importance in the design and manufacture of microfluidic devices. The macromolecules are modeled with finitely extendable nonlinear elastic (FENE) chains, and dissipative particle dynamics (DPD) approach is used to investigate the cross-stream migration of macromolecules under pressure driven flow in micro- and nanochannels. The results show that the chains migrate away from the wall and move toward the channel centerline in wide channels where the chains are under weak confinement. In the wide channel, both the thickness of the depletion layer near the wall and the migration toward the channel centerline increase with the flow strength, and these simulation results agree well with well-known experimental observations. Under weak confinement, the center-of-mass distribution of the chains exhibits a local minimum in the centerline accompanied with two symmetric off-center peaks, and the migration away from the wall increases with the increase of channel width. However, the chains migrate away from the channel centerline in narrow channels where the chains are under strong confinement, and the migration increases with the flow strength.

Key words: Cross-stream migration, Dissipative particle dynamics, Macromolecules, Microfluidic devices