Flow investigation in a microchannel with a flow disturbing rib

• We studied the flow around a flow-disturbing rib in a microchannel.
• The flow was characterized using both the μ-PIV and the electrodiffusion techniques.
• A validated CFD code was used to assess the effect of key design parameters.
• The blockage ratio and the Re greatly affect the formation of recirculation zones.
• We proposed correlations for predicting the length of the bottom recirculation zone.

The purpose of this work is to study the flow around a flow-disturbing rib in a rectangular microchannel and to investigate the effect of key design parameters (i.e. the rib height and length as well as the Reynolds number) on the size of the reattachment length of the recirculation zones and the wall shear stress profiles in the vicinity of the rib. Initially the wall shear rate along the channel as well as the velocity field were experimentally determined using the electrodiffusion technique and the μ-PIV method, respectively. The experimental results are then used for validating a CFD code. Finally, the CFD code was employed for investigating the effect of the design parameters on the flow characteristics by performing a parametric study based on the Design of Experiments (DOE) and the Response Surface Methodology (RSM). It was found that the recirculation length in the laminar regime is affected mainly by the Re value and the rib height, whereas in the turbulent regime it is affected strongly by the rib height and slightly also by the rib length. Based on our results two new correlations, which can predict the length of the bottom recirculation zone with reasonable accuracy, are proposed and can be used for the design of microdevices.