The proper orthogonal decomposition and dynamic mode decomposition of minimal channel flow

Name: Worapat Piensuk

Organization : King Mongkut's University of Technology Thonburi. Faculty of Engineering

Name: Peerapong Kumkhuntod

Organization : King Mongkut's University of Technology Thonburi. Faculty of Engineering

Name: Wichayaporn Suthanupaphwuth

Organization : King Mongkut's University of Technology Thonburi. Faculty of Engineering

Name: Kamthon Septham

Organization : King Mongkut's University of Technology Thonburi. Faculty of Engineering

Email : kamthon.sep@mail.kmutt.ac.th

keyword: Direct numerical simulation

ThaSH: Decomposition (Chemistry)

; Proper orthogonal decomposition

ThaSH: Decomposition (Mathematics)

; Dynamic mode decomposition

; Wall turbulence

; Minimal flow unit

Abstract: Wall turbulence is the turbulent flow in a region adjacent to the wall or the surface enclosing the fluid. The study of wall turbulence provides a better understanding of the underlying physics, thus, the improvement of drag reduction strategies. Theoretically solving the Navier-Stokes equations seems to be an ideal approach to extract knowledge of fluid motions. However, wall turbulence cannot be easily described due to the existence of essentially strongly nonlinearity. Therefore, here is where numerical simulation comes into play as it allows us to investigate fluid motions. Direct numerical simulation (DNS) employed in this work is a widely accepted method due to its superior accuracy. One of the most significant features of wall turbulence is the self-sustaining mechanisms, and the minimal flow unit (MFU) is the smallest computational domain capable of capturing this phenomenon. Not only that MFU can dramatically reduce computational costs, but the results from the MFU is also much less complicated than that of the full channel. The numerical data obtained from DNS is then analysed via the proper orthogonal decomposition (POD) and the dynamic mode decomposition (DMD) which allows complex structures of turbulence to be extracted and decomposed into fundamental structures. In this study, the streamwise and spanwise computational domain of the channel was chosen to be 0.6πh and 0.18πh, respectively, where h is the channel half-height. DNS is performed using Channelflow-1.4.2 which gives the velocity distribution in the domain during the time interval 0 ≤ t ≤ 400 at friction Reynolds number of approximately 200. The time duration between two successive timesteps is 0.1. The results from DMD indicate that the most dominant structure likely corresponds to a streak-like structure which is the crucial component of the self-sustaining mechanisms. Other less important structures are responsible for the complexity in the flow. The results from POD can also identify the same dominant structure.

King Mongkut's University of Technology North Bangkok. Central Library

Address: BANGKOK

Email: library@kmutnb.ac.th

Created: 2020

Modified: 2025-06-11

Issued: 2025-06-11

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BibliograpyCitation : In Ubon Ratchathani University Faculty of Engineering. The 11th TSME International Conference on Mechanical Engineering 2020 (TSME-ICoME11) (pp.239-245) Ubon Ratchathani : Ubon Ratchathani University

eng

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