Numerical study on the effect of planar normal and Halbach magnet arrays on micromixing

The effective mixing process is critical in biological and chemical processes. The main objective of the present study is to investigate the influence of normal and Halbach magnet arrays on the mixing performance of a three-inlet micromixer numerically. In this microdevice, ferrofluid is injected into the center inlet, and water is injected into two other inlets. The influence of Remanent Flux Density Norm (RFDN), number of magnets, magnet distance from the main microchannel entrance, and inlet flow rate is considered. It is revealed that the micromixer with magnets exhibits a 165% improvement in the mixing efficiency compared to the one with no magnetic field. The results show that increasing the magnetic field does not always increase the mixing quality. Even in some cases, it has a negative effect. It is demonstrated that the mixing efficiency is strongly influenced by the magnet arrangement. An optimal position is found for the magnet arrangement to achieve the maximum mixing efficiency of 91%. Contrary to the normal configuration, Halbach magnet array creates a parabolic profile for flux density. Halbach array can improve the mixing performance, depending on all magnets' RFDN. The proposed microchannel can be used as a useful device for biological applications.