Analysis of Coherent Structure of Turbulent Flows in the Rectangular Open-Channel Using LES

- Journal title : Journal of The Korean Society of Civil Engineers
- Volume 34, Issue 5, 2014, pp.1435-1442
- Publisher : Korean Society of Civil Engeneers
- DOI : 10.12652/Ksce.2014.34.5.1435

Title & Authors

Analysis of Coherent Structure of Turbulent Flows in the Rectangular Open-Channel Using LES

Ban, Chaewoong; Choi, Sung-Uk;

Ban, Chaewoong; Choi, Sung-Uk;

Abstract

This study presented numerical simulations of smooth-bed flows in the rectangular open-channel using the source code by OpenFOAM. For the analysis of the turbulent flow, Large Eddy Simulations were carried out and the dynamic sub-grid scale model proposed by Germano et al. (1991) is used to model the residual stress term. In order to analyze the coherent structure, the uw quadrant method proposed by Lu and Willmarth (1973) is used and the contribution rate and the fraction time of the instantaneous Reynolds stress are obtained in the Reynolds stress. The results by the present study are analyzed and compared with data from previous laboratory studies and direct numerical simulations. It is found that the contribution rate of the ejection events is larger than that of sweep events over the buffer layer in the open-channel flow over the smooth bed, however, the frequency of the sweep event is higher than that of the ejection events.

Keywords

Turbulence;Coherent structure;Bursting phenomena;uw quadrant threshold;Large eddy simulation;OpenFOAM;

Language

Korean

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