Deformation of gas-liquid interfaces in a non-Newtonian fluid at high throughputs inside a microfluidic device and effect of an expansion on bubble breakup mechanisms

Abstract

This work is focused on the development of a compact continuous process for the production of food foams with controlled properties. Cross-shaped channels of infra millimeter size are used and the two-phase flow pattern is analyzed in order to identify the mechanisms of bubble deformation and breakup at very high velocities [~2–20 m s−1]. Two different microcrochannel designs are used, differing by the presence of an abrupt expansion in one of the devices. Similar breakup mechanisms are observed in both devices in the cross-shaped channels and an additional local elongational flow was identified in the expansion. The expansion was found to intensify bubble breakup. All the experiments are carried out with the same gas content and the same liquid mix prepared from biosourced molecules (xanthan gum and whey proteins). A dimensional analysis is proposed in order to model the diameter of bubbles at the moment of their formation.