Characterization of fluid flow in a microchannel with a flow disturbing step

The flow around a flow-disturbing step in a rectangular microchannel is studied by measuring the wall shear rate along the channel, using the electrodiffusion technique and by determining the velocity field using the μ-PIV method. A parametric study based on the Design of Experiments (DOE) and the Response Surface Methodology (RSM) was then performed, and the effect of key design parameters on the flow characteristics was numerically investigated using CFD simulations. The computational results are in excellent agreement with the corresponding experimental ones. The CFD simulations cover both the laminar and the turbulent flow regime. It was revealed that in both flow regimes the step height has a major influence on the recirculation length. However, the Reynolds number (Re) value affects the recirculation length only in the laminar region, while the step length seems to have no significant effect compared to the Re and the step height. Finally, new correlations are proposed predicting the length of the bottom recirculation zone with reasonable accuracy and can be used as rough guidelines for the design of microdevices.