Numerical and experimental investigation of an efficient convergent–divergent micromixer

Abstract

Experimental and numerical investigations on the mixing quality of a novel micromixer are conducted. A micromixer made by PDMS is fabricated to evaluate the mixing process in comparison with the numerical simulations. The main purpose of the present paper is to propose an efficient divergence–convergence based macromixer for low-Reynolds-number flows. The effect of inlet velocity (Reynolds number), number of mixing cycles and blockage ratio on the mixing performance of the micromixer is investigated. The results reveal that the mixing efficiency (ME) increases with injection velocity, number of cycles and blockage ratio. For the range of Reynolds number from 9 to 75, the Dean vortices are not formed, however, generation of expansion vortices is the main factor of mixing for Re > 19. It is demonstrated that the value of ME/ΔP (Pa−1) for the micromixer with three, four, five and six mixing cycles is 6.36, 2.23, 0.74, and 0.5, respectively. In addition, the micromixer with the blockage ratio of 0.25 reaches the mixing efficiency of 100%. Relatively high values of ME/ΔP makes the proposed micromixer suitable for practical applications in which the Reynolds number is less than 75.