Polymer stretching and alignment under the hierarchy of coherent vortices in turbulence

At which scales do vortices in turbulence effectively stretch polymers? To answer this question, we conduct direct numerical simulations of turbulence and the Brownian dynamics simulations of the finitely extensible nonlinear elastic (FENE) dumbbell model. A scale-decomposition analysis based on a bandpass filter allows us to identify the dominant scale for polymer stretching. Furthermore, we explain the scale-dependent contribution to polymer stretching by focusing on the persistence of the stretching process of polymers induced by each-scale vortices.