Numerical Simulation of Mixing in Active Micromixers Using SPH

In the present study, the mixing process of two-phase flow in active micromixers with straight and wavy channels is investigated, using the meshless method of SPH. Active micromixers with oscillating stir bar and different modes of sinusoidal wavy-walled channel, known as raccoon and serpentine, are considered, and their performances are compared. Simulations are performed for the most important dimensionless parameters of the problem, including amplitude of the wavy-walled channel, alpha, wavelength of the wavy walls, lambda, and Reynolds number, Re. In search for an optimal design for micromixers, a wide range of test simulations including 0.1 <= alpha <= 0.7, 1 <= lambda <= 4 and 15 <= Re <= 100 is carried out. The results reveal that for all the sinusoidal wavy-walled channels, the mixing improvement strongly depends on the wavelength of the walls rather than the wave amplitude. In active-raccoon micromixers, the mixing improvement smoothly increases with increases in the wave amplitude, whereas in active-serpentine micromixers, it decreases. As a general result, the active-raccoon micromixers exhibit better efficiency, compared with other types of micromixers, especially at Re = 45. However, the active-serpentine micromixer is inefficient in a wide range of wave amplitudes and wavelengths.