Modeling of redox electrochemical MHD and three-dimensional CFD simulations of transient phenomena in microfluidic cells

Computational fluid dynamics simulations of redox electrochemical magneto-hydrodynamics (MHD) covering a large parameter space have been done to establish the effects of redox species concentration, electrode area, and magnetic field strength and orientation on the limiting current. Simulations of milli-electrode and microelectrode systems show similarities and differences between the two. Potential sweep and potential step simulations using time-accurate solution algorithms enabled accurate capture of transient phenomena which is crucial to the development of lab-on-a-chip flow control applications. Power-law correlations reported in previous experimental investigations of milli-electrodes are found to be less accurate for microelectrodes and nano-electrodes suggesting possible effects of multidimensional diffusion. Further, the orientation of the magnetic field in relation to the electrode surface has a strong influence on the flow field. Interesting and complex flow features are observed in the post-processed still images and animations. This work advances redox MHD simulations by incorporating important aspects in the models that were not considered in previous models. Our simulations based on these new models provide new insight into redox electrochemical MHD.