TY - CONF
T1 - Modification of hairpin auto-generation process in turbulent channel flows due to polymer stress
AU - Kim, Kyoungyoun
AU - Sureshkumar, R.
N1 - Funding Information:
This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (No. 2010-0007901) and the National Science Foundation under grant CBET-1055219 .
Publisher Copyright:
© 2011 International Symposium on Turbulence and Shear Flow Phenomena TSFP. All rights reserved.
PY - 2011
Y1 - 2011
N2 - To study the influence of dynamical interactions between turbulent vortical structures and polymer stress on turbulent friction drag reduction, a series of simulations were performed for channel flow at Re#X003C4; =395. The initial eddy extracted by the conditional averages for the Q2 event from fully turbulent Newtonian flow is self-consistently evolved in the presence of polymer stresses by utilizing the FENE-P model (finitely extensible nonlinear elastic-Peterlin). The initial polymer conformation fields are given by the solutions of FENE- P model equations for the Newtonian mean shear. For a relatively low Weissenberg number, defined as the ratio of fluid relaxation time to the time scale of viscous diffusion, (We = 50) the generation of new vortices is inhibited by polymer-induced counter torques, which results in fewer vortices in the buffer layer. However, the head of primary hairpin is unaffected by the polymer stress. For larger values of We(#X022DB;100), the hairpin head becomes weaker and vortex auto-generation and Reynolds stress growth are almost entirely suppressed.
AB - To study the influence of dynamical interactions between turbulent vortical structures and polymer stress on turbulent friction drag reduction, a series of simulations were performed for channel flow at Re#X003C4; =395. The initial eddy extracted by the conditional averages for the Q2 event from fully turbulent Newtonian flow is self-consistently evolved in the presence of polymer stresses by utilizing the FENE-P model (finitely extensible nonlinear elastic-Peterlin). The initial polymer conformation fields are given by the solutions of FENE- P model equations for the Newtonian mean shear. For a relatively low Weissenberg number, defined as the ratio of fluid relaxation time to the time scale of viscous diffusion, (We = 50) the generation of new vortices is inhibited by polymer-induced counter torques, which results in fewer vortices in the buffer layer. However, the head of primary hairpin is unaffected by the polymer stress. For larger values of We(#X022DB;100), the hairpin head becomes weaker and vortex auto-generation and Reynolds stress growth are almost entirely suppressed.
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M3 - Paper
AN - SCOPUS:85048606178
T2 - 7th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2011
Y2 - 28 July 2011 through 31 July 2011
ER -