Experiments were conducted in a water tunnel using a large flat plate to study skin friction reduction in a turbulent boundary layer with slot injection of solutions of polyethylene oxide(polyox). The local skin friction drag reduction and mean polymer concentration profiles were measured at various locations for a range of conditions. A development length is required for the local drag reduction to reach a maximum for a given set of injection and flow conditions. Mean polymer concentration profiles at downstream locations, where drag reductions begin to decrease, resemble passive contaminant profiles in the initial diffusion zone. This polymer-extended initial diffusion zone is a region of relatively large drag reduction.
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