http://orcid.org/0000-0001-9576-1571
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ABSTRACT
The non-linear energy transfer between the most energetic structures in the logarithmic layer (referred to here as large-scales) and those in the roughness sublayer induced by the presence of the roughness (referred to here as small-scales) is studied in a boundary layer developing over a rough-wall consisting of staggered cubes with a plan area packing density, = 25%, in the wind tunnel using combined Particle Image Velocimetry (PIV) and Hot-Wire Anemometry (HWA). The energy transfer between the mean flow, large-scales and small-scales is quantified using scale decomposition of the Turbulent Kinetic Energy (TKE) budget. Multi-time delay Linear Stochastic Estimation (LSE) is used to decompose the flow into large- and small-scales. Using scale decomposition of the TKE budget it is shown that although the greatest mean energy transfer occurs between the mean flow and the small-scales a significant instantaneous energy transfer between the large- and small-scales exists. Finally, it is confirmed through spatio-temporal cross correlation that the non-linear relationship that exists between large-scale coherent structures and small-scales created through interaction with the roughness elements is linked to instantaneous energy transfer between these structures.
Acknowledgments
The authors should like to thank Mr. Thibaut Piquet for his technical support during the experimental programme. The authors also acknowledge the financial support of the French National Research Agency through the research grant URBANTURB N° ANR-14-CE22-0012-01.
Disclosure statement
No potential conflict of interest was reported by the authors.
ORCID
Karin Blackman http://orcid.org/0000-0001-9576-1571