Imperial College London
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Dr. Oliver Buxton

Faculty of Engineering, Department of Aeronautics

Reader in Experimental Fluid Mechanics
 
 
 
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Contact

 

+44 (0)20 7594 5118o.buxton Website CV

 
 
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Location

 

213City and Guilds BuildingSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Breda:2018:10.1063/1.5019668,
author = {Breda, M and Buxton, O},
doi = {10.1063/1.5019668},
journal = {Physics of Fluids},
pages = {035109--1--035109--24},
title = {Influence of coherent structures on the evolution of an axisymmetric turbulent jet},
url = {http://dx.doi.org/10.1063/1.5019668},
volume = {30},
year = {2018}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - The role of initial conditions in affecting the evolution toward self-similarity of an axisymmetric turbulent jet is examined. The jet’s near-field coherence was manipulated by non-circular exit geometries of identical open area, D2e, including a square and a fractal exit, for comparison with a classical round orifice jet. Hot-wire anemometry and 2D-planar particle image velocimetry experiments were performed between the exit and a location 26De downstream, where the Reynolds stress profiles are self-similar. This study shows that a fractal geometry significantly changes the near-field structure of the jet, breaking up the large-scale coherent structures, thereby affecting the entrainment rate of the background fluid into the jet stream. It is found that many of the jet’s turbulent characteristics scale with the number of eddy turnover times rather than simply the streamwise coordinate, with the entrainment rate (amongst others) found to be comparable across the different jets after approximately 3-4 eddies have been overturned. The study is concluded by investigating the jet’s evolution toward a self-similar state. No differences are found for the large-scale spreading rate of the jets in the weakly self-similar region, so defined as the region for which some, but not all of the terms of the mean turbulent kinetic energy equation are self-similar. However, the dissipation rate of the turbulent kinetic energy was found to vary more gradually in x than predicted according to the classical equilibrium theories of Kolmogorov. Instead, the dissipation was found to vary in a non-equilibrium fashion for all three jets tested.
AU  - Breda,M
AU  - Buxton,O
DO  - 10.1063/1.5019668
EP  - 1
PY  - 2018///
SN  - 1070-6631
SP  - 035109
TI  - Influence of coherent structures on the evolution of an axisymmetric turbulent jet
T2  - Physics of Fluids
UR  - http://dx.doi.org/10.1063/1.5019668
UR  - http://hdl.handle.net/10044/1/58384
VL  - 30
ER  -
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