Cooperative drag reduction in turbulent flows using polymer additives and superhydrophobic walls

The injection of long-chain polymer additives and the water-repellent (or superhydrophobic) texturing of submerged solid walls, have both evolved independently over the years into effective, stand-alone methods for frictional drag reduction in wall-bounded turbulent flows. Experiments performed in turbulent Taylor-Couette flow demonstrate that the two techniques, when combined carefully, result in an additive effect, producing significant enhancements in the overall level of drag reduction achieved.