Fig. 2.

Phase diagram of cross-stream diffusion-based species transport in microchannels. Three regions—(i), (ii), and (iii)—were defined to establish the validity of the various analytical models: Region (i) corresponds to cases where the aspect ratio is low or modest and concentration differences can persist across the depth direction, Region (ii) corresponds to cases where the aspect ratio is large and where concentration differences do not persist across the depth direction (owing to rapid depth-wise diffusion), and Region (iii) corresponds to where the axial diffusion is not negligible. A parametric analysis was performed using the data points denoted by the stars and circles, which will be used for the discussion in Sect. 4.2.2