Numerical study of a novel spiral-type micromixer for low Reynolds number regime

The present study proposes a novel spiral-shaped micromixer to provide high mixing performance at low Reynolds numbers encountered in many microfluidic systems. The liquid mixing is analyzed with Reynolds numbers from 0.1 to 10, molecular diffusivities from 10⁻⁸ to 10⁻¹¹, and aspect ratios from 0.5 to 1.5. In the present simulations, the Dean number is not sufficient to cause the formation of primary rotating vortices. It is revealed that as the Reynolds number increases, the mixing performance is improved. The results demonstrate that the magnitude of ME/Δp (Pa⁻¹) is 0.236, 0.018, 0.011, 0.009, and 0.007 at Reynolds numbers of 0.1, 2, 5, 8, and 10, respectively indicating the high mixing performance of the proposed micromixer. It is found that the mixing efficiency is improved slightly with the molecular diffusivity. The mixing efficiency of the micromixer is 94.44, 93.76, 93.1, and 92.7% for molecular diffusivities of 10⁻⁸, 10⁻⁹, 10⁻¹⁰, and 10⁻¹¹ m²/s, respectively. In addition, the proposed micromixer reaches 99.5% for the aspect ratio of 1. Due to relatively high values of ME/Δp, the proposed micromixer with square cross-section can be suggested as a good candidate for biochemical applications.