Numerical analysis of electroosmotic mixing in a heterogeneous charged micromixer with obstacles

The mixing and flow characteristics are numerically investigated for an electroosmotic flow through a heterogeneous charged micromixer with obstacles both at the top and bottom walls arranged in inline and staggered order by varying the obstruction angle (theta). The results are presented by varying the Debye parameter (kappa), magnitude of the zeta potential (vertical bar zeta vertical bar), and obstruction angle in the range of 10 <= kappa <= 100, 1 <= vertical bar zeta vertical bar <= 4, and 60 degrees <= theta <= 120 degrees, respectively. Results reveal that the strength of the recirculation zone is the highest for theta = 90 degrees and it enhances with kappa and vertical bar zeta vertical bar,and moreover, the strength is always higher for the staggered arrangement of obstacles as compared to the inline order. For inline arrangement of the obstacles, the value of mixing efficiency (ME) decreases with x as well as vertical bar zeta vertical bar and the highest values are seen for theta = 90 degrees. For the staggered arrangement of obstacles, the variation of ME with kappa is not monotonic; rather, it strongly depends on vertical bar zeta vertical bar and theta. The flow rate increases with the increase in kappa and it is the lowest for theta = 90 degrees and importantly, the flow rate is always more for inline arrangements of the obstacles.