Resolvent analysis of suboptimal control for turbulent friction drag reduction

2016 ◽  
Vol 2016 (0) ◽  
pp. 0315
Author(s):  
Satoshi NAKASHIMA ◽  
Koji FUKAGATA ◽  
Mitul LUHAR
AIAA Journal ◽  
2020 ◽  
Vol 58 (9) ◽  
pp. 4178-4180
Author(s):  
Shiho Hirokawa ◽  
Masahiro Ohashi ◽  
Kaoruko Eto ◽  
Koji Fukagata ◽  
Naoko Tokugawa

2007 ◽  
Vol 2007 (0) ◽  
pp. _115-a_
Author(s):  
Koji FUKAGATA ◽  
Stefan KERN ◽  
Philippe Chatelain ◽  
Petros KOUMOUTSAKOS ◽  
Nobuhide KASAGI

2007 ◽  
Vol 2007 (0) ◽  
pp. _115-1_-_115-4_
Author(s):  
Koji FUKAGATA ◽  
Stefan KERN ◽  
Philippe Chatelain ◽  
Petros KOUMOUTSAKOS ◽  
Nobuhide KASAGI

2018 ◽  
Vol 2018 (0) ◽  
pp. OS1-16
Author(s):  
Aika KAWAGOE ◽  
Satoshi NAKASHIMA ◽  
Mitul LUHAR ◽  
Koji FUKAGATA

2017 ◽  
Vol 12 (2) ◽  
pp. JFST0013-JFST0013 ◽  
Author(s):  
Masanari FUJIMURA ◽  
Kaoru IWAMOTO ◽  
Akira MURATA ◽  
Mitsutoshi MASUDA ◽  
Hirotomo ANDO ◽  
...  

Author(s):  
Riko Uekusa ◽  
Aika Kawagoe ◽  
Yusuke Nabae ◽  
Koji Fukagata

Abstract In the present study, we numerically manipulate the mean velocity profile of a turbulent channel flow and assess the friction drag reduction performance by using resolvent analysis. Building on the implication obtained from Kühnen et al. (Nat. Phys., Vol. 14, 2017, pp. 386–390) that modifying mean velocity profile flat leads to significant drag reduction, we first introduce two functions for turbulent mean velocity, which can express ‘flattened’ profiles: one is derived based on the turbulent viscosity model proposed by Reynolds & Tiederman (J. Fluid Mech., Vol. 658, 2010, pp. 336–382), and the other is based on the mean velocity profile of laminar flow. These functions are used as the mean velocity profile for the resolvent analysis, and the flatness of the resulting profiles is characterized by two different measures. As a result, we confirm that, friction drag reduction is achieved if the turbulent mean velocity profile is ‘flattened’. However, we also find that the flatness of the mean velocity profile in the center of the channel alone is not enough to evaluate the drag reduction performance.


2008 ◽  
Vol 9 ◽  
pp. N35 ◽  
Author(s):  
Koji Fukagata ◽  
Stefan Kern ◽  
Philippe Chatelain ◽  
Petros Koumoutsakos ◽  
Nobuhide Kasagi

2021 ◽  
Vol 33 (7) ◽  
pp. 075115
Author(s):  
Chi Wai Wong ◽  
Xiaoqi Cheng ◽  
Dewei Fan ◽  
Wenfeng Li ◽  
Yu Zhou

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