Turbid two-phase slug flow in a microtube: Simultaneous visualization of structure and velocity field

Frequency domain optical coherence tomography with phase-resolved algorithm is presented to perform high-resolution, cross-sectional imaging of turbid two-phase slug flow in a microtube. Imaging and quantifying the interfacial structure and velocity field in a turbid two-phase flow are important to understand the mechanism of bioreactions and flow dynamics in biological systems. The authors demonstrate here that optical coherence tomography can measure detailed interfacial structures, bubble velocity, and velocity field inside liquid slugs. The radial liquid velocity was quantified without refraction correction. Two toroidal vortices per liquid slug were visualized which is the essential mechanism for radial heat and mass transfers.