Abstract
Skin-friction drag reduction effect by polymer additives in a turbulent channel flow is investigated by means of PIV and LIF measurements. We employed a fluorescently-labeled polymer in order to capture the polymer behavior in the flow. As a preliminary experiment, the fluorescently-labeled polymer is visualized in a rotating flow and compared with a dyed polymer. The fluorescently-labeled polymer shows to form thread-like structures for longer time than the dyed polymer. The PIV measurement of the turbulent channel flow with the dyed polymer shows the decrease of the Reynolds shear stress, which implies the skin-friction drag reduction.
