Particle transport in patterned cylindrical microchannels

An Eulerian model (convection–diffusion– migration equation) to evaluate particle transport in patchy heterogeneous cylindrical microchannels is presented. The objective of this model is to capture the effect of surface chemical heterogeneity on deposition and particle transport in cylindrical microchannels with fully developed Poiseuille flow velocity profile. Surface heterogeneity is modeled as alternate bands of attractive and repulsive regions on the channel wall to facilitate systematic continuum type evaluation. The results indicate that particles tend to preferentially collect at the leading edge of the favorable sections and the extent of this deposition can be controlled by changing Peclet number. Also, it is shown that particles tend to travel further along the microchannel length for heterogeneous channels compared to homogeneously favorable channels. In addition, the study evaluates the effect of the frequency of these stripes on the transport behavior and provides the average collection rate depending on favorable surface coverage fraction. This analysis shows how the existing microchannel/capillary transport models could possibly be modified by incorporating surface interactions and chemical heterogeneity.