Enhancing mixing efficiency in curved channels: A 3D study of bi-phasic Dean-Taylor flow with high spatial and temporal resolution

Abstract

Two-phase (Taylor flow) and curved reactors (Dean flow) are conventionally used to improve mixing in flow systems by reducing axial dispersion and narrowing residence time distributions. However, when the two flow regimes are superposed in bi-phasic flow in curved channels (Dean-Taylor flow), the result is poorly understood due to experimental and computational limitations, despite its widespread practical implementation. In this study, we introduce a novel high-efficient computational strategy to investigate Dean-Taylor flow providing highly detailed spatial and time-resolved data of the fluid dynamics of this flow regime. This approach demonstrates how the counter-rotating vortices characteristics of Taylor flow lose their symmetry and develop three-dimensional flow patterns in curved channels. The appearance of radial and transverse velocity components promoted by centrifugal forces can significantly enhance mixing/mass transfer in comparison to pure Dean and pure Taylor flow. However, a certain level of curvature (e.g., Dean numbers > 5) is required to significantly break the barrier between the Taylor flow vortices. The implications of this new knowledge are far-reaching and critical for designing future flow processes, as demonstrated here for the synthesis of iron nanoparticles with narrow size distributions.