Turbulence and intermittency in homogeneous isotropic flows of elastoviscoplastic fluids

Elastoviscoplastic (EVP) fluids behave as a viscoelastic solid when the applied stress is low, and as a viscous liquid when the applied stress is above a critical value known as the yield stress. Examples include mud, lava, and toothpaste. We make direct numerical simulations of a number of EVP fluids in homogeneous isotropic turbulence with microscale Reynolds number~435. Spectral and scale-by-scale analyses reveal a new apparent scaling of the kinetic energy E~k^(-2.3) beyond the inertial range. In addition, we define a "non-Newtonian dissipation" term arising from viscoelastic forces in the Navier-Stokes equation. This non-Newtonian dissipation takes more extreme values as plasticity increases, leading to an increase in intermittency, as observed in plots of the structure functions.