Elastic turbulence hides in the small scales of inertial polymeric turbulence

Abstract: Gaining a fundamental understanding of turbulent flows of dilute polymer solutions has been a challenging and outstanding problem for a long time. In this letter, we examine homogeneous, isotropic polymeric turbulence at large Reynolds and Deborah numbers through direct numerical simulations. While at the largest scales of the flow inertial turbulence exists, we find that the flow is fundamentally altered from Newtonian turbulence below the Kolmogorov scale. We demonstrate that `Elastic Turbulence' exists at the smallest scales of polymeric turbulence by quantifying multiple statistical properties of the flow - energy spectrum and flux in Fourier space as well as the spatial statistics of the velocity field - the structure functions and kurtosis, and energy dissipation. Our results show the coexistence of two fundamentally distinct types of turbulence in polymeric fluids and point to the ubiquity of elastic turbulence, which was hitherto only known to exist for negligible inertia.