Drag reduction in high reynolds number turbulent channel flow

Name: Vasin Satthavisut

LCSH: Kasetsart University -- Theses. M.Eng. (Aerospace Engineering) 2017

Classification :.LCCS: TL574.D7

LCSH: Kasetsart University. Department of Aerospace Engineering -- Theses

LCSH: Drag (Aerodynamics)

LCSH: Turbulent boundary layer

LCSH: Turbulence

LCSH: Reynolds number

LCSH: Skin friction (Aerodynamics)

Abstract: A conventional control of near-wall coherent structures works effectively in reducing a drag at low Reynolds number, but becomes less effective as the Reynolds number increases. Recent studies observed that the large-scale structures in the outer layer become more important as the Reynolds number increases. The objective of this study is to explore alternative coherent structure control strategies for skin-friction drag reduction at high Reynolds number flow. The study is based on a Large-Eddy Simulation (LES) of turbulent channel flow at a moderate-high friction Reynolds number of 934. The target of the new control strategies is to suppress near-wall coherent structures as well as and/or large-scale structures in the outer layer. An opposition control, body force actuators and a combination of the two are chosen as the control schemes for near-wall, off-wall and combined controls, respectively. A large computational box up to 8πh and 3πh in streamwise and spanwise, are chosen to capture the dynamic of large-scale structures. The results show that the most drag reduction was observed in the combined control. The characteristics affected by various controls were examined to understand the mechanisms of drag reduction. For the Reτ tested here, the computational box sizes of 2πh and πh in streamwise and spanwise, are sufficiently large enough to reproduce a reliable prediction of the amount of drag reduction and one-point turbulent statistics which are comparable with the largest box.

Kasetsart University. Office of the University Library

Address: Bangkok

Email: tdckulib@ku.ac.th

Name: Vejapong Juttijudata

Role: Thesis Advisor

Name: Arpiruk Hokpunna

Role: Thesis Co-Advisor

Created: 2017

Modified: 2023-06-06

Issued: 2023-06-06

วิทยานิพนธ์/Thesis

application/pdf

URL: https://kasetsart.idm.oclc.org/login?url=https://www.lib.ku.ac.th/KUthesis/2560/vasin-sat-all.pdf

CallNumber: TL574.D7.V37

eng

DegreeName: Master of Engineering

Level: Master's Degree

Descipline: Aerospace Engineering

Grantor: Kasetsart University

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