Effect of Patch Length on Electroosmotic Mixing Characteristics Inside a Heterogeneously Charged Micromixer

The flow and mixing attributes within a micromixer with heterogeneous surface charge is investigated. The finite element approach is used to numerically compute the governing transport equations. By varying the patch lengths (HP) and the diffusive Peclet number (Pe) in the physically reasonable span, the flow field, dimensionless flow rate, recirculation velocity (UR), species concentration field, and mixing efficiency ( \(\eta\) ) are explored. It reveals that as patch length is increased, the size of the regions of recirculation and UR both augment while an increment in patch length diminishes the flow rate. Moreover, as HP increases, the homogeneity of the outlet dimensionless species concentration improves and gets closer to 0.5. There is a critical Pe (Pecri,1) over which mixing efficiency is 100% for all HP and Pecri,1 increases as HP increases. Contrarily, for Pe > Pecri,1, mixing efficiency decreases as Pe increases.