Axial dispersion in segmented gas-liquid flow: effects of alternating channel curvature

Abstract

The effects of channel curvature on the axial dispersion in segmented gas-liquid flows are studied computationally in a two-dimensional setting using a finite-volume/front-tracking method. Passive tracer particles are used to visualize and quantify the axial dispersion. The molecular diffusion is modeled by random walk of tracer particles. It is found that there is significant axial dispersion in serpentine channels even in the absence of molecular diffusion. The lubricating thin liquid layer that persists on the wall of a straight channel is periodically broken in the serpentine channel leading to enhanced axial dispersion. It is also found that the axial dispersion is always larger in the serpentine channel than that in the straight channel but the effects of channel curvature are more pronounced at high Peclet numbers, i.e., Pe > 10(4). A model is proposed based on the difference between the liquid film thicknesses on the inner and outer side of the bend in the limit as Pe ->infinity. Good agreement is found between the computational results and the model when the liquid slug is well mixed by the chaotic advection.