“…Stroock and McGraw [9] approximated the complex three-dimensional flow field using a two dimensional lid-driven cavity model that was tuned to provide qualitative agreement to experimental data and studied the effect of varying two geometric parameters: the asymmetry factor of the groove and the number of grooves in each cycle; Liu et al [10] studied the influence of different fluid properties and a large concentration gradient on mixing at Re = 1 and 10 for a fixed geometry; Aubin et al [11,12] investigated numerically the effect of three geometric parameters: the groove depth, the groove width and the number of grooves per cycle, using a particle tracking method to visualize and quantify the mixing performance; Kang and Kwon [13] applied a coloured particle tracking method to study numerically the mixing performance of three types of grooved micromixers including the SHM; Yang et al [14] studied the effects of varying herringbone groove offset, depth, and angle, as well as the ratio of inlet channel width to mixing channel width by applying CFD to nine configurations defined with an array given by the Taguchi method; Li and Chen [15] used the Lattice Boltzmann method to study numerically the effect on mixing performance of the asymmetry factor and the number of grooves per half-cycle; Hassel and Zimmerman [16] presented a numerical study of the flow through the SHM to characterize the effect of the grooves on moving fluid across the channel, in particular of the groove depth in Re range 0-15 and of the number of grooves per half-cycle; Lynn and Dandy [17] evaluated numerically the generation of helical flows in the slanted groove micromixer (SGM) and its optimization, i.e., the increment of transverse flow, by varying the ratio of the length of the grooves to the neighbouring ridge for a given groove depth and channel aspect ratio, and discussed the implications of translating the optimized parameters to the SHM design; Ansari and Kim [18] used a numerical procedure that combines three-dimensional Navier-Stokes analysis and a numerical optimization technique, the response surface method (RSM), to enhance mixing performance by optimizing the groove using the ratio of groove depth to channel height and angle of the groove; Singh et al [19] introduced a new simplified formulation of the mapping method [20] to make it much simpler to implement and applied the method to optimize three micromixer designs including the SHM for which groove depth and number of grooves per half-cycle were used as parameters; very recently, Cortes-Quiroz et al [21,22] presented a multi-criteria design optimization methodology for micromixers based on the integration of CFD with numerical optimization techniques and applied it for the optimization of four geometries of the SHM to obtain good mixing performance with low pressure loss.…”