Modeling wall effects in capillary electrochromatography

A volume averaging technique for modeling electroosmotic and pressure driven flow in microchannels is applied to a packed capillary electrochromatography column. This model can be applied to fluid flow in both porous and open channels and can account for porosity variation in the column due to packing and zeta potential mismatches between the wall and the packing material. Numerical results are presented and compared with experimental results from the literature. Several different porosity models are shown to produce similar concentration profiles and allow the model to reproduce wall effects observed in experimental columns.