Enhanced mixing in dual-mode cylindrical magneto-hydrodynamic (MHD) micromixer

Abstract

The proposed cylindrical magneto-hydrodynamic (MHD) micromixer developed in this study was a geometrically modified conventional T-micromixer combining the characteristics of passive and active micromixers. Characterization was achieved by observing the mixing efficiencies of NaCl solution (1% concentration) based on supplied electrical potential and inlet flow rates. The design mainly aimed to utilize the pumping capability of the magneto-hydrodynamic principle as a secondary element to give counter pumping energy towards inlet flows, such that perturbation of fluid increased mixing performance. NaCl solution was mixed by advection through the stretching and folding by micro-vortices generated in the mixing reservoir. The cylindrical MHD micromixer achieved its highest mixing index of 99.42% at Re = 40 with 3 V of direct-current potential (VDC) supplied to the electrodes. Mixing efficiency increased in a considerably similar and linear pattern for Re = 5, 10, 20, and 40 within the electrical potential range of 0.5 ≤ V ≤ 3.0. Control was gained by manipulating the external electrical potential source which only required a smaller capacity of direct-current voltage sources. Overall, the proposed cylindrical MHD micromixer, which emphasizes the use of inexpensive material and simple design, has been experimentally proven to be practical as compared to the passive and active micromixers found in the literature.