Direct numerical simulation of spatially developing turbulent boundary layer for skin friction drag reduction by wall surface-heating or cooling

2012 ◽  
Vol 13 ◽  
pp. N34 ◽  
Author(s):  
Yukinori Kametani ◽  
Koji Fukagata
2011 ◽  
Vol 681 ◽  
pp. 154-172 ◽  
Author(s):  
YUKINORI KAMETANI ◽  
KOJI FUKAGATA

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.


Author(s):  
Hidetoshi Iijima ◽  
Hidemi Takahashi ◽  
Seigo Koga ◽  
Monami Sasamori ◽  
Yoshimi Iijima ◽  
...  

2022 ◽  
Author(s):  
Md Abdur Razzak ◽  
Yong Dong Cui ◽  
Jonathan Tay ◽  
Zhen Wei Teo ◽  
Thirukumaran Nadesan ◽  
...  

2019 ◽  
Vol 9 (23) ◽  
pp. 5199
Author(s):  
Hidemi Takahashi ◽  
Hidetoshi Iijima ◽  
Mitsuru Kurita ◽  
Seigo Koga

A unique approach to evaluate the reduction of skin friction drag by riblets was applied to boundary layer profiles measured in wind tunnel experiments. The proposed approach emphasized the turbulent scales based on hot-wire anemometry data obtained at a sampling frequency of 20 kHz in the turbulent boundary layer to evaluate the skin friction drag reduction. Three-dimensional riblet surfaces were fabricated using aviation paint and were applied to a flat-plate model surface. The turbulent statistics, such as the turbulent scales and intensities, in the boundary layer were identified based on the freestream velocity data obtained from the hot-wire anemometry. Those turbulent statistics obtained for the riblet surface were compared to those obtained for a smooth flat plate without riblets. Results indicated that the riblet surface increased the integral scales and decreased the turbulence intensity, which indicated that the turbulent structure became favorable for reducing skin friction drag. The proposed method showed that the current three-dimensional riblet surface reduced skin friction drag by about 2.8% at a chord length of 67% downstream of the model’s leading edge and at a freestream velocity of 41.7 m/s (Mach 0.12). This result is consistent with that obtained by the momentum integration method based on the pitot-rake measurement, which provided a reference dataset of the boundary layer profile.


2006 ◽  
Vol 552 (-1) ◽  
pp. 353 ◽  
Author(s):  
WENDY C. SANDERS ◽  
ERIC S. WINKEL ◽  
DAVID R. DOWLING ◽  
MARC PERLIN ◽  
STEVEN L. CECCIO

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