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{Buxton:2019:10.1103/PhysRevFluids.4.034603,
author = {Buxton, O and Breda, M and Dhall, K},
doi = {10.1103/PhysRevFluids.4.034603},
journal = {Physical Review Fluids},
pages = {034603:1--034603:17},
title = {Importance of small-scale anisotropy in the turbulent/nonturbulent interface region of turbulent free shear flows},
url = {http://dx.doi.org/10.1103/PhysRevFluids.4.034603},
volume = {4},
year = {2019}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - There has been much debate over the past decade or so over the scaling of the thickness of the turbulent/nonturbulent (TNT) interface for turbulent shear flows. It is generally considered to consist of the outer viscous superlayer, in which viscous processes are significant, and an inner turbulent sublayer which is dominated by inertial processes. Various authors have stated that the interface thickness scales with the Taylor length scale λ while others state that it scales with the Kolmogorov length scale η [Buxton et al., Phys. Fluids 23, 061704 (2011)]. Frequently, only self-similar turbulent flows are considered in which a single value of either λ or η is sufficient to scale various phenomena, including the thickness of the TNT interface. In this paper we show that for flows which are not self-similar the local Kolmogorov length scale increases quite significantly as one moves closer to the boundary between the turbulent and nonturbulent fluid. We find that the variation of this local Kolmogorov length scale with normal distance from the TNT boundary may be collapsed by the local Kolmogorov length scale computed from the TNT boundary itself. We subsequently show that this variation in local Kolmogorov length scale occurs concurrently with an increase in the small-scale anisotropy in the TNT interface. This anisotropy peaks at the boundary between the viscous superlayer and the turbulent sublayer, suggesting that these two sublayers are in fact quite distinct from one another. We show that these results hold for a number of different TNT interfaces from various flows and with the bulk turbulence being in a variety of states of development. The local viscous scaling that we obtain, along with an increase in anisotropy primarily driven by an increased magnitude of velocity gradients in the TNT-boundary-normal direction, leads us to draw an analogy between TNT interfaces and the wall in wall-bounded turbulence.
AU  - Buxton,O
AU  - Breda,M
AU  - Dhall,K
DO  - 10.1103/PhysRevFluids.4.034603
EP  - 1
PY  - 2019///
SN  - 2469-990X
SP  - 034603
TI  - Importance of small-scale anisotropy in the turbulent/nonturbulent interface region of turbulent free shear flows
T2  - Physical Review Fluids
UR  - http://dx.doi.org/10.1103/PhysRevFluids.4.034603
UR  - http://hdl.handle.net/10044/1/68197
VL  - 4
ER  -
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