Landel, Julien R. and Caulfield, C. P. and Woods, Andrew W. (2012) Meandering Due to Large Eddies and the Statistically SelfSimilar Dynamics of QuasiTwoDimensional Jets. Journal of Fluid Mechanics, 692. pp. 347368. DOI 10.1017/jfm.2011.518

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Abstract
We investigate experimentally the structure of quasitwodimensional plane turbulent jets discharged vertically from a slot of width into a fluid confined between two relatively close rigid boundaries with gap . At large vertical distances the jet structure consists of a meandering core with large counterrotating eddies, which develop on alternate sides of the core. Using particle image velocimetry, we observe an inverse cascade typical of quasitwodimensional turbulence where both the core and the eddies grow linearly with and travel at an average speed proportional to . However, although the present study concerns quasitwodimensional confined jets, the jets are selfsimilar and the mean properties are consistent with both experimental results and theoretical models of the timeaveraged properties of fully unconfined planar twodimensional jets. We believe that the dynamics of the interacting core and large eddies accounts for the Gaussian profile of the mean vertical velocity as shown by the spatial statistical distribution of the core and eddy structure. The lateral excursions (caused by the propagating eddies) of this highspeed central core produce a Gaussian distribution for the timeaveraged vertical velocity. In addition, we find that approximately 75 % of the total momentum flux of the jet is contained within the core. The eddies travel substantially slower (at approximately 25 % of the maximum speed of the core) at each height and their growth is primarily attributed to entrainment of ambient fluid. The frequency of occurrence of the eddies decreases in a stepwise manner due to merging, with a welldefined minimum value of the corresponding Strouhal number .
Item Type:  Article 

Uncontrolled Keywords:  2011AREP; IA62; 
Subjects:  99  Other 
Divisions:  99  Other 
Journal or Publication Title:  Journal of Fluid Mechanics 
Volume:  692 
Page Range:  pp. 347368 
Identification Number:  10.1017/jfm.2011.518 
Depositing User:  Sarah Humbert 
Date Deposited:  17 Apr 2012 08:48 
Last Modified:  23 Jul 2013 10:04 
URI:  http://eprints.esc.cam.ac.uk/id/eprint/2465 
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