Turbulent drag reduction with liquid-infused surfaces

We present turbulent skin friction reduction over liquid-impregnated surfaces in Taylor-Couette flow. The surface of the inner cylinder of the facility contains square grooves, with widths from 100 $\mu$m to 800 $\mu$m and a fixed liquid area of half the total area. Alkane liquids are infused in the surface with viscosities from $\sim$1/3 to 2 times that of water. For Reynolds numbers up to $Re_d$=10,500 corresponding to a flow shear of $\tau$=50 Pa, we achieve drag reduction exceeding 30\%, three times higher than ever reported for liquid-infused surfaces.