Re-examining the logarithmic dependence of the mean velocity distribution in polymer drag reduced wall-bounded flow

A re-examination of the logarithmic dependence of the mean velocity distribution in polymer drag reduced flows shows that drag reducing polymers modify the von Karman coefficient and, in channel flow, eradicate the log-layer at high drag reductions. It is also found that the ultimate profile, corresponding to the state of maximum drag reduction is not logarithmic. (c) 2012 American Institute of Physics. [doi:10.1063/1.3681862]