AbstractDrag reduction in turbulent pipe flow by means of boundary and centerline injection of long hair‐like asbestos fibers has been investigated. Pressure drop and mean velocity profiles were measured at various Reynolds numbers and injection rates in order to study some mechanistic aspects of drag reduction in water‐fiber and polymer‐fiber systems. Drag reduction in a water‐fiber system is attributed to a decrease in the momentum transfer in the turbulent‐core region, whereas synergism has been found to be a wall p