Momentum and mass transfer on sandpaper-roughened surfaces in pipe flow

A series of three electrochemically obtained nickel pipes with different surface roughness degree has been used in this study. In respect to momentum transfer, these rough surfaces exhibit similar patterns in terms of friction factor, friction similarity function, and rough-to-smooth friction factor ratio. The mass transfer is investigated with the electrochemical technique which exploits the red-ox reactions of potassium ferri- and ferro-cyanides. The gain in mass transfer enhancement is positive against the friction development in the range 3000–30,000 for the Reynolds number.