Grid and subgrid-scale interactions in viscoelastic turbulent flow and implications for modeling

Abstract

Using direct numerical simulations of turbulent plane channelflow of homogeneous polymer solutions, described by the FinitelyExtensible Nonlinear Elastic-Peterlin (FENE-P) rheological constitutive model, a-priori analyses of the filtered momentum and FENE-Pconstitutive equations are performed. The influence of the polymeradditives on the subgrid-scale (SGS) energy is evaluated by comparing the Newtonian and the viscoelastic flows, and a severe suppression of SGS stresses and energy is observed in the viscoelastic flow.All the terms of the transport equation of the SGS kinetic energy forFENE-P fluids are analysed, and an approximated version of this equation for use in future large eddy simulation closures is suggested.The terms responsible for kinetic energy transfer between grid-scale(GS) and SGS energy (split into forward/backward energy transfer) areevaluated in the presence of polymers. It is observed that the probability and intensity of forward scatter events tend to decrease in thepresence of polymers