Continuum Modeling and Numerical Simulation of Active Suspensions in Curved Channels

This paper presents a two-fluid model to simulate the behavior of uniformly oriented active suspensions in curved annular channels. Active suspensions consist of self-propelled particles suspended in a fluid that exhibit complex collective behavior through interactions with their surrounding environment. The proposed model captures key interactions between the fluid and particle phases, including drag and lift forces, and allows the analysis of flow patterns and particle distributions. The study investigates the flow of active suspensions in an annular channel with a rectangular cross-section, where stable secondary flow patterns develop, characterized notably by Dean vortices. Numerical simulations are used to examine the effects of channel curvature and aspect ratio on the dynamics of these suspensions. Results reveal that increased curvature intensifies the formation of Dean vortices, which significantly affect the particle distribution. Additionally, larger aspect ratios increase the strength of the secondary flow and enhance particle segregation. Model comparison to direct numerical simulations shows a qualitatively good agreement in predicting particle distribution profiles.