Hydrodynamics of the developing region in hydrophobic microchannels: A dissipative particle dynamics study

摘要

Dissipative particle dynamics (DPD) is becoming a popular particle-based method to study flow throughnmicrochannels due to the ease with which the presence of biological cells or DNA chains can be modeled. Manynlab-on-a-chip devices require the ability to manipulate the transport of cells or DNA chains in the fluid flow.nMicrochannel surfaces coated with combinations of hydrophilic and hydrophobicmaterials have been found usefulnfor this purpose. In this work we study numerically the hydrodynamics of a steady nonuniform developing flownbetween two infinite parallel plates with hydrophilic and hydrophobic surfaces using the DPD. The hydrophobicnand hydrophilic surfaces are modeled using partial-slip and no-slip boundary conditions, respectively, in thensimulations. We also propose a method to model the inflow and outflow boundaries for the DPD simulations.nThe simulation results of the developing flow are in good agreement with analytical solutions from continuumntheory for no-slip and partial-slip surfaces. The entrance region constitutes a considerable fraction of the channelnlength in miniaturized devices. Thus it is desirable for the length of the developing region to be short as mostnmicrofluidic devices such as cell or DNA separators and mixers are designed for the developed flow field. Wenstudy the effect of a hydrophilic strip near the inlet of a hydrophobic microchannel on the developing length.Wenfind that the presence of the hydrophilic strip significantly reduces the developing length.