Influence of Elastic Forces in Transition Phenomenon
Analice Costacurta Brandi1; Ellen Silva Gervazoni1; Marcio Teixeira de Mendonça2; Leandro Franco de Souza3
1 Universidade Estadual Paulista - UNESP/Presidente Prudente; 2 Instituto de Aeronautica e Espaco; 3 Universidade de São Paulo - ICMC/São Carlos
doi:10.20906/CPS/COB-2015-2074
Resumo
Several flows of practical interest are of non-newtonian fluids and it is often desirable to know if these flows are in a laminar or turbulent state. A class of these fluids is classified as viscoelastic fluids. In this paper the growth rate of Tollmien-Schlichting waves is studied for Poiseuille flow for a non-Newtonian fluid. The mathematical model adopted for the non-Newtonian fluid extra-stress tensor is the Oldroyd-B. The analysis is carried out by means of Direct Numerical Simulation. The Navier-Stokes equations along with the Oldroyd-B constitutive equation are solved using a high-order finite differences numerical model. The results show that the amplification rates obtained differs from Newtonian fluid as the Weissenberg number increases. Comparisons are presented considering the maximum amplification rates for Newtonian and non-Newtonian fluid for different values of dimensionless parameters.
Palavras-chave: laminar-turbulent transition ; Linear Stability Theory ; viscoelastic fluids; Direct Numerical Simulation