A study on mixing performance of dean flows through spiral micro-channel under various effects

This paper reports a parametric study on mixing performance of dean flows in spiral micro-channels using the finite element method. Many important parameters such as the Reynolds number (Re), Peclet number (Pe), flow rate ratio between two species flows (α), and ratio of diffusion coefficient (β) were examined for enhancing mixing efficiency (η_mix). The numerical results matched well with those predicted by the theoretical model. In addition, mixing efficiency of dean flows in the spiral micro-channel generally increased with increasing Re, particularly at low Pe. This is in contrast to results obtained for straight micro-channels with the same channel length. Mixing efficiency (η_mix) was affected significantly by the Pe number ranging from 10³ to 4 × 10⁴, and it increases with a decrease in Pe. In addition, η_mix varied remarkably with α, and the worst point, at which the η_mix decreases by 50%, occurs when α is around 2.0. Otherwise, η_mix is shown to be influenced slightly by β. Furthermore, a new generalized correlation was proposed for predicting the pressure drop throughout a spiral micro-channel effectively. These results provide good suggestions for optimizing mixing efficiency of dean flows in spiral micro-channels, which can be used for further biological and chemical analyses.