  By tracking small particles in the bulk of an intensely turbulent flow, we
show that even a very small concentration of long-chain polymers disrupts the
usual turbulent energy cascade. The polymers affect scales much larger than
their physical size, from the dissipation range to the inertial range. The
effect depends strongly on the polymer concentration. While the
dissipative-scale statistics change continuously as the polymer concentration
is increased, the inertial-range energy transfer rate is only altered by the
polymer additives when the concentration is above a threshold (approximately 5
parts per million by weight for the polymer we used).
