TY - JOUR
T1 - Direct numerical simulation of spatially developing turbulent boundary layers with uniform blowing or suction
AU - Kametani, Yukinori
AU - Fukagata, Koji
N1 - Funding Information:
The authors are grateful to Drs Shinnosuke Obi and Simon Illingworth (Keio University), Drs Nobuhide Kasagi and Yosuke Hasegawa (The University of Tokyo), Dr Kaoru Iwamoto (Tokyo University of Agriculture and Technology) and Dr Yoshitsugu Naka (Ecole Centrale Lille) for fruitful discussion. We also thank Dr Parviz Moin (Stanford University) and Dr Xiaohua Wu (Royal Military College of Canada) for comments concerning the baseline results. This work was supported through Grant-in-Aid for Scientific Research (A) (No. 20246036) by the Ministry of Education, Culture, Sports and Technology of Japan (MEXT), the silent supersonic aircraft research program of the Japan Aerospace Exploration Agency (JAXA), and the Keio University Global COE program, the Center for Education and Research of Safe, Secure and Symbiotic System Design.
PY - 2011/8/25
Y1 - 2011/8/25
N2 - Direct numerical simulation (DNS) of spatially developing turbulent boundary layer with uniform blowing (UB) or uniform suction (US) is performed aiming at skin friction drag reduction. The Reynolds number based on the free stream velocity and the 99% boundary layer thickness at the inlet is set to be 3000. A constant wall-normal velocity is applied on the wall in the range,-'0.01U∞ ≤ Vctr ≤ 0.01U ∞. The DNS results show that UB reduces the skin friction drag, while US increases it. The turbulent fluctuations exhibit the opposite trend: UB enhances the turbulence, while US suppresses it. Dynamical decomposition of the local skin friction coefficient cf using the identity equation (FIK identity) (Fukagata, Iwamoto & Kasagi, Phys. Fluids, vol. 14, 2002, pp. L73-L76) reveals that the mean convection term in UB case works as a strong drag reduction factor, while that in US case works as a strong drag augmentation factor: in both cases, the contribution of mean convection on the friction drag overwhelms the turbulent contribution. It is also found that the control efficiency of UB is much higher than that of the advanced active control methods proposed for channel flows.
AB - Direct numerical simulation (DNS) of spatially developing turbulent boundary layer with uniform blowing (UB) or uniform suction (US) is performed aiming at skin friction drag reduction. The Reynolds number based on the free stream velocity and the 99% boundary layer thickness at the inlet is set to be 3000. A constant wall-normal velocity is applied on the wall in the range,-'0.01U∞ ≤ Vctr ≤ 0.01U ∞. The DNS results show that UB reduces the skin friction drag, while US increases it. The turbulent fluctuations exhibit the opposite trend: UB enhances the turbulence, while US suppresses it. Dynamical decomposition of the local skin friction coefficient cf using the identity equation (FIK identity) (Fukagata, Iwamoto & Kasagi, Phys. Fluids, vol. 14, 2002, pp. L73-L76) reveals that the mean convection term in UB case works as a strong drag reduction factor, while that in US case works as a strong drag augmentation factor: in both cases, the contribution of mean convection on the friction drag overwhelms the turbulent contribution. It is also found that the control efficiency of UB is much higher than that of the advanced active control methods proposed for channel flows.
KW - boundary layer control
KW - drag reduction
KW - turbulent boundary layers
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U2 - 10.1017/jfm.2011.219
DO - 10.1017/jfm.2011.219
M3 - Article
AN - SCOPUS:80052178374
SN - 0022-1120
VL - 681
SP - 154
EP - 172
JO - Journal of Fluid Mechanics
JF - Journal of Fluid Mechanics
ER -