The stepped channel design have been used since more than 3,000 years. It is understood that low flows behave as successions of free-jets (i.e. nappe flow) while large discharges skim over the pseudo-bottom formed by the step edges. For a range of intermediate flow rates, a transition flow regime takes place. The dominant feature is stagnation on the horizontal step face associated with signifi...

In this work, we investigate the behavior of dilute and semidilute polymer solutions flowing in a microfluidic flow focusing device, in which an inlet stream is stretched by two balanced lateral streams. By varying the flow rates in the inlet and lateral channels and their ratio, several types of flow transitions are observed and the resulting velocity fields are analyzed both upstream and down...