LAUSR

This study experimentally examines the dispersion of soluble substances in liquid-filled micro-channels. The purpose of our study is to examine the effect of channel geometry on the laminar dispersion of solutes in variously shaped micro-channels. We used an image analysis technique based on absorption photometry that enables quantification of a solute concentration field. We conducted experiments using rough-walled channels and investigated the effect of the irregularity of the wall surface on solute transport. The experimental results revealed that the solute dispersion in the streamwise direction depends on wall roughness in a complicated manner. The formation of a dead water region plays an important role in the enhancement of solute dispersion in rough-walled channels. To evaluate the solute dispersion more quantitatively, we proposed a model that accounts for the effect of channel geometry by reference to previous studies. The proposed model well describes the dispersion coefficient obtained from our experiments, which uses variously shaped channels over a wide range of Péclet numbers.