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Wakes of wall-bounded turbulent flows past patches of circular cylinders

Published online by Cambridge University Press:  14 April 2020

C. Nicolai Open the ORCID record for C. Nicolai [Opens in a new window] ,
S. Taddei ,
C. Manes Open the ORCID record for C. Manes [Opens in a new window]  and
B. Ganapathisubramani Open the ORCID record for B. Ganapathisubramani [Opens in a new window]
C. Nicolai*
Affiliation:
Aerodynamics and Flight Mechanics Group, University of Southampton, University Road, SouthamptonSO17 1BJ, UK
S. Taddei
Affiliation:
Aerodynamics and Flight Mechanics Group, University of Southampton, University Road, SouthamptonSO17 1BJ, UK
C. Manes
Affiliation:
Department of Environment, Land and Infrastructure Engineering, Politecnico di Torino, Corso Duca degli Abruzzi, 24, 10129, Torino, Italy
B. Ganapathisubramani
Affiliation:
Aerodynamics and Flight Mechanics Group, University of Southampton, University Road, SouthamptonSO17 1BJ, UK
*
†Email address for correspondence: [email protected]
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Abstract

The properties of the wake generated by a porous body fully immersed in a turbulent boundary layer are experimentally assessed. The body consists of an array of cylinders, with diameter $d$, covering a circular patch of diameter $D$. For fixed $d$ and $D$, by increasing the number of cylinders, $N_{c}$, within the patch, the wake properties are systematically tested under different levels of density ($\unicode[STIX]{x1D719}$ $=$ covered planar area per total surface) and compared to the flow past a solid body of equivalent diameter and height ($H$). Some insights on the complex flow developing in the wake are captured: $\unicode[STIX]{x1D719}$ varying in the range 2 %–24 % results in the flow meandering among the cylinders and bleeding from the top, the sides and the trailing edge of the patch. The interplay between trailing edge and top bleeding prevents wake entrainment, locking the wake longitudinal extent to 5–7 patch diameters, regardless of the density level. Due to the finite body vertical extent, a third shear layer develops from the top of the patch. The interaction between the top shear layer and the lateral ones leads to a mutual alteration, namely a nonlinear growth not captured by the classical mixing layer theory. Nevertheless, on the horizontal plane at the patch mid-height, the mean flow recovers, exhibiting a self-similar decay. Surprisingly, the recovery is well described by the classical planar wake theory and the characteristic scales, namely the maximum velocity deficit and the wake half-width, evolve linearly as proposed by Wygnanski et al. (J. Fluid Mech., vol. 168, 1986, pp. 31–71).

JFM classification

Wakes/Jets: Wakes Wakes/Jets: Shear layers Turbulent Flows: Turbulent boundary layers
Type
JFM Papers
Information
Journal of Fluid Mechanics , Volume 892 , 10 June 2020 , A37
Copyright
© The Author(s), 2020. Published by Cambridge University Press

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References

Ahmadian, R., Falconer, R. & Bockelmann-Evans, B. 2012 Far-field modelling of the hydro-environmental impact of tidal stream turbines. J. Renew. Energy 38 (1), 107–116.CrossRefGoogle Scholar
Baidya Roy, S., Pacala, S. W. & Walko, R. L. 2004 Can large wind farms affect local meteorology? J. Geophys. Res. 109, D19101.CrossRefGoogle Scholar
Castro, I. P. 1971 Wake characteristics of two-dimensional perforated plates normal to an air-stream. J. Fluid Mech. 46 (3), 599–609.CrossRefGoogle Scholar
Champagne, F. H., Pao, Y. H. & Wygnanski, I. J. 1976 On the two-dimensional mixing region. J. Fluid Mech. 74 (2), 209–250.CrossRefGoogle Scholar
Chang, K. & Constantinescu, G. 2015 Numerical investigation of flow and turbulence structure through and around a circular array of rigid cylinders. J. Fluid Mech. 776, 161–199.CrossRefGoogle Scholar
Chang, W.-Y., Constantinescu, G. & Tsai, W. F. 2017 On the flow and coherent structures generated by a circular array of rigid emerged cylinders placed in an open channel with flat and deformed bed. J. Fluid Mech. 831, 1–40.CrossRefGoogle Scholar
Chen, Z., Ortiz, A., Zong, L. & Nepf, H. 2012 The wake structure behind a porous obstruction and its implications for deposition near a finite patch of emergent vegetation. Water Resour. Res. 48, W09517.CrossRefGoogle Scholar
De Langre, E. 2008 Effects of wind on plants. Annu. Rev. Fluid Mech. 40, 141–168.CrossRefGoogle Scholar
Dimotakis, P. E. 1991 Turbulent free shear layer mixing and combustion. High Speed Flight Propul. Syst. 137, 265–340.Google Scholar
Gardiner, B., Peltola, H. & Kellomäki, S. 2000 Comparison of two models for predicting the critical wind speeds required to damage coniferous trees. Ecol. Model. 129 (1), 1–23.CrossRefGoogle Scholar
Ghisalberti, M. & Nepf, H. M. 2002 Mixing layers and coherent structures in vegetated aquatic flows. J. Geophys. Res. 107 (C2), 3-1–3-11.CrossRefGoogle Scholar
Hobeck, J. D. & Inman, D. J. 2012 Artificial piezoelectric grass for energy harvesting from turbulence-induced vibration. Smart Mater. Struct. 21 (10), 105024.CrossRefGoogle Scholar
Kemp, J. L., Harper, D. M. & Crosa, G. A. 2000 The habitat-scale ecohydraulics of rivers. Ecol. Engng 16 (1), 17–29.CrossRefGoogle Scholar
Myers, L. E. & Bahaj, A. S. 2012 An experimental investigation simulating flow effects in first generation marine current energy converter arrays. J. Renew. Energy 37 (1), 28–36.CrossRefGoogle Scholar
Nepf, H. M. 2012 Flow and transport in regions with aquatic vegetation. Annu. Rev. Fluid Mech. 44, 123–142.CrossRefGoogle Scholar
Nicolle, A. & Eames, I. 2011 Numerical study of flow through and around a circular array of cylinders. J. Fluid Mech. 679, 1–31.CrossRefGoogle Scholar
Patel, R. P. 1973 An experimental study of a plane mixing layer. AIAA J. 11 (1), 67–71.CrossRefGoogle Scholar
Poggi, D., Katul, G. & Albertson, J. 2006 Scalar dispersion within a model canopy: measurements and three-dimensional Lagrangian models. Adv. Water Resour. 29 (2), 326–335.CrossRefGoogle Scholar
Pope, S. 2000 Turbulent Flows. Cambridge University Press.CrossRefGoogle Scholar
Rajewski, D. A., Takle, E. S., Prueger, J. H. & Doorenbos, R. K. 2016 Toward understanding the physical link between turbines and microclimate impacts from in situ measurements in a large wind farm. J. Geophys. Res. 121 (22), 13392–13414.Google Scholar
Raupach, M. R., Finnigan, J. J. & Brunet, Y. 1996 Coherent eddies and turbulence in vegetation canopies: the mixing-layer analogy. In Boundary-Layer Meteorology 25th Anniversary Volume, 1970–1995, pp. 351–382. Springer.CrossRefGoogle Scholar
Rominger, J. T. & Nepf, H. M. 2011 Flow adjustment and interior flow associated with a rectangular porous obstruction. J. Fluid Mech. 680, 636–659.CrossRefGoogle Scholar
Sumner, D. 2013 Flow above the free end of a surface-mounted finite-height circular cylinder: a review. J. Fluids Struct. 43, 41–63.CrossRefGoogle Scholar
Symes, C. R. & Fink, L. E. 1977 Structure and Mechanisms of Turbulence 1 (ed. Fiedler, H.), Springer.Google Scholar
Taddei, S., Manes, C. & Ganapathisubramani, B. 2016 Characterisation of drag and wake properties of canopy patches immersed in turbulent boundary layers. J. Fluid Mech. 798, 27–49.CrossRefGoogle Scholar
Vanderwel, C. & Tavoularis, S. 2015 Scalar dispersion by coherent structures. In TSFP DIGITAL LIBRARY ONLINE. Begel House Inc.Google Scholar
Vennell, R. 2011 Tuning tidal turbines in-concert to maximise farm efficiency. J. Fluid Mech. 671, 587–604.CrossRefGoogle Scholar
Wygnanski, I., Champagne, F. & Marasli, B. 1986 On the large-scale structures in two-dimensional, small-deficit, turbulent wakes. J. Fluid Mech. 168, 31–71.CrossRefGoogle Scholar
Zhou, J. & Venayagamoorthy, S. K. 2019 Near-field mean flow dynamics of a cylindrical canopy patch suspended in deep water. J. Fluid Mech. 858, 634–655.CrossRefGoogle Scholar
Zong, L. & Nepf, H. 2012 Vortex development behind a finite porous obstruction in a channel. J. Fluid Mech. 691, 368–391.CrossRefGoogle Scholar