Grid and subgrid-scale interactions in viscoelastic turbulent flow and implications for modelling |
| |
Authors: | M Masoudian CB da Silva FT Pinho |
| |
Institution: | 1. Transport Phenomena Research Center, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias s/n, 4200-465 Porto, Portugal;2. IDMEC, Instituto Superior Técnico, Universidade de Lisboa, Pav. Mecanica I, LASEF, Av. Rovisco Pais, 1049-001 Lisboa, Portugal |
| |
Abstract: | Using direct numerical simulations of turbulent plane channel flow of homogeneous polymer solutions, described by the Finitely Extensible Nonlinear Elastic-Peterlin (FENE-P) rheological constitutive model, a-priori analyses of the filtered momentum and FENE-P constitutive equations are performed. The influence of the polymer additives 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 for FENE-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) are evaluated in the presence of polymers. It is observed that the probability and intensity of forward scatter events tend to decrease in the presence of polymers. |
| |
Keywords: | Direct numerical simulation polymer drag reduction large eddy simulation turbulence modelling: subgrid-scale small scale intermittency |
|
|