High-fidelity measurements in channel flow with polymer wall injection

Abstract

Streamwise velocity profiles and their wall-normal derivatives were used to investigate the properties of turbulent channel flow in the low polymer drag reduction regime ( to ), as realized via polymer injection at the channel surface. Streamwise velocity data were obtained over a friction Reynolds number ranging from to using the single-velocity-component version of molecular tagging velocimetry (1c-MTV). This adaptation of the MTV technique has the ability to accurately capture instantaneous profiles at very high spatial resolution ( data points per wall-normal profile), and thus generate well-resolved derivative information as well. Owing to this ability, the present study is able to buil..