Numerical simulation of turbulent flow through a straight square duct. (5th December 2015)

• Record Type: Journal Article
• Authors: Yao, Jun; Zhao, Yanlin; Fairweather, Michael
• Is Part Of: Applied thermal engineering. Volume 91(2015:Dec.)
• Page Start: 800
• Page End: 811
• Publication Date: 2015-12-05
• Subjects: Duct flow -- Secondary flow -- Reynolds number -- Turbulence -- Large eddy simulation; Heat engineering -- Periodicals; Heating -- Equipment and supplies -- Periodicals; Periodicals; 621.40205
• DOI: 10.1016/j.applthermaleng.2015.08.065
• Languages: English
• ISSNs: 1359-4311

Abstract

Abstract: Turbulent duct flows are investigated using large eddy simulation at bulk Reynolds numbers, from 4410 to 250, 000. Mean secondary flow is found to reveal the existence of two streamwise counter-rotating vortices in each corner of the duct. Turbulence-driven secondary motions that arise in duct flows act to transfer fluid momentum from the centre of the duct to its corners, thereby causing a bulging of the streamwise velocity contours towards the corners. As Reynolds number increases, the ratio of centreline streamwise velocity to the bulk velocity decreases and all turbulent components increase. In addition, the core of the secondary vortex in the lower corner-bisector tends to approach the wall and the corner with increasing Reynolds number. The turbulence intensity profiles for the low Reynolds number flows are quite different from those for the high Reynolds number flows. Typical turbulence structures in duct flows are found to be responsible for the interactions between ejections from wall and this interaction results in the bending of the ejection stems, which indicates that the existence of streaky wall structures is much like in a channel flow. Graphical abstract: Highlights: Turbulent duct flows are investigated using large eddy simulation. Duct flows at bulk Reynolds number, 4410–250, 000, are considered. Typical secondary flows are captured in the ducts. All components turbulent intensity increases with Reynolds number. Turbulence structures in duct flows are responsible for the interactions between ejections from wall.