Design of a micromixer with alternating flattened tubes

The present paper proposes a novel design for a chaotic micromixer utilizing alternating flattened tubes (AFTs). Three-dimensional Navier–Stokes equations and a convection–diffusion transport equation are solved to perform numerical simulations for a broad Reynolds number (Re) range of 0.1–150. The impact of alternating pitch angle (θ = 30°–75°), Re, and dynamic viscosity (μ = 10⁻³–10⁻¹) on the performance of the AFT micromixer is assessed. The results reveal that the mixing index is improved with θ due to an enhancement in the molecular diffusion and induced chaotic advection. When Re = 0.1, the AFT micromixer can provide excellent mixing quality compared to a T-shaped micromixer while its pressure drop (Δp) is less than 7 Pa. It is found that molecular diffusion is a dominant mechanism of micromixing when Re is low (0.1) and chaotic advection plays a major role when Re is an order of 10 and 100. The results demonstrate that mixing energy cost is reduced by increasing θ when Re is kept constant, meaning that higher mixing quality can be achieved by enhancing θ while Δp increases slightly.