Effects of polymer additive on turbulent bulk flow: The polymer concentration dependence

Abstract

We report an experimental study of the effects of polymer additives on the turbulent bulk flow. Our results confirm that both the acceleration fluctuation a and the velocity fluctuation u of the flow are suppressed when the polymer additives are present and the suppression effect on a is much stronger. We further found that polymer additives enhance the anisotropy of the flow at small scales, but do not affect the anisotropy at large scale very much. These results are qualitatively in agreement with a recent theory which predicts that only scales smaller than a critical scale are affected by the polymer additives.