Articles

Large eddy simulation of flow over urban vegetated regions

  • YAN Chao ,
  • CUI Guixiang ,
  • ZHANG Zhaoshun
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  • School of Aerospace Engineering, Tsinghua University, Beijing 100084, China

Received date: 2016-11-22

  Revised date: 2016-12-17

  Online published: 2017-02-21

Abstract

Vegetation exerts notable influences on urban microenvironment through biophysical processes. Studying the flow over urban vegetated region requires a proper treatment of the vegetation canopy. A large eddy simulation (LES) method is developed in the present work, which can well simulate the canopy flow. Using LES the turbulent flow over a model vegetation canopy is investigated under the neutral atmospheric condition. Each vegetation element consisting of a sphere-shaped tree crown and a cylindrical trunk is fully resolved. The resulting turbulence statistics and the drag force on vegetation agree well with the measurements from the corresponding wind-tunnel experiment. Two other numerical representations of vegetation canopies, referred to as drag element approach and drag crown approach, have also been developed to assess their performances. The drag crown approach yields better agreement between numerical results and experimental measurements than the traditional drag element approach, thus providing a promising numerical model for simulating canopy turbulence.

Cite this article

YAN Chao , CUI Guixiang , ZHANG Zhaoshun . Large eddy simulation of flow over urban vegetated regions[J]. Science & Technology Review, 2017 , 35(3) : 51 -56 . DOI: 10.3981/j.issn.1000-7857.2017.03.005

References

[1] Bonan G B. Forests and climate change:Forcings, feedbacks, and the climate benefits of forests[J]. Science, 2008, 320(5882):1444-1449.
[2] Arya S P. Introduction to micrometeorology[M]. 2nd ed. California:Aca-demic Press, 2001.
[3] 季劲钧, 苗曼倩. 不均匀植被分布对地表面和大气边界层影响的数值试验[J]. 大气科学, 1994, 18(3):293-302. Ji Jinjun, Miao Manqian. Atmospheric Science[J]. Chinese Journal of At-mospheric Sciences, 1994, 18(3):293-302.
[4] Baldocchi D, Falge E, Gu L, et al. Fluxnet:A new tool to study the tem-poral and spatial variability of ecosystem-scale carbon dioxide, water vapor, and energy flux densities[J]. Bulletin of the American Meteorolog-ical Society, 2001, 82(11):2415-2434.
[5] Patton E, Horst T, Sullivan P, et al. The canopy horizontal array turbu-lence study[J]. Bulletin of the American Meteorological Society, 2011, 92(5):593-611.
[6] Kaimal J C, Finnigan J J. Atmospheric boundary layer flows:Their structure and measurement[M]. New York:Oxford University Press, 1994.
[7] Fernando H J S. Fluid dynamics of urban atmospheres in complex ter-rain[J]. Annual Review of Fluid Mechanics, 2009, 42(1):365-389.
[8] 尹协远. 关于植被中湍流的研究[J]. 力学进展, 1991, 25(4):444-456. Yin Xieyuan. Studies on turbulence in vegetation[J]. Advances in Me-chanics, 1991, 25(4):444-456.
[9] Finnigan J. Turbulence in plant canopies[J]. Annual Review of Fluid Mechanics, 2000, 32(1):519-571.
[10] Lee S H. Further development of the vegetated urban canopy model in-cluding a grass-covered surface parametrization and photosynthesis ef-fects[J]. Boundary-Layer Meteorology, 2011, 140(2):315-342.
[11] Nepf H M. Flow and transport in regions with aquatic vegetation[J]. Annual Review of Fluid Mechanics, 2012, 44(1):123-142.
[12] Belcher S E, Harman I N, Finnigan J J. The wind in the willows:Flows in forest canopies in complex terrain[J]. Annual Review of Fluid Mechanics, 2012, 44(1):479-504.
[13] 赵鸣. 大气边界层动力学[M]. 北京:高等教育出版社, 2006:203-208. Zhao Ming. Dynamics of atmospheric boundary layer[M]. Beijing:High-er Education Press, 2006:203-208.
[14] Bonan G B. Ecological climatology[M]. 2nd ed. Cambridge:Cambridge University Press, 2008.
[15] Harman I, Finnigan J. A simple unified theory for flow in the canopy and roughness sublayer[J]. Boundary-Layer Meteorology, 2007, 123(2):339-363.
[16] Harman I, Finnigan J. Scalar Concentration profiles in the canopy and roughness sublayer[J]. Boundary-Layer Meteorology, 2008, 129(3):323-351.
[17] Poggi D, Porporato A, Ridolfi L, et al. The effect of vegetation density on canopy sub layer turbulence[J]. Boundary-Layer Meteorology, 2004, 111(3):565-587.
[18] Haverd V, Böhm M, Raupach M. The effect of source distribution on bulk scalar transfer between a rough land surface and the atmosphere[J]. Boundary-Layer Meteorology, 2010, 135(3):351-368.
[19] Finnigan J, Shaw R, Patton E. Turbulence structure above a vegetation canopy[J]. Journal of Fluid Mechanics, 2009, 637(20):387-424.
[20] Pan Y, Chamecki M, Isard S A. Large eddy simulation of turbulence and particle dispersion inside the canopy roughness sublayer[J]. Jour-nal of Fluid Mechanics, 2014, 753(16):499-534.
[21] Brunet Y, Finnigan J J, Raupach M R. A wind tunnel study of air flow in waving wheat:Single point velocity statistics[J]. Boundary-Layer Meteorology, 1994, 70(1):95-132.
[22] Böhm M, Finnigan J J, Raupach M R, et al. Turbulence structure with-in and above a canopy of bluff elements[J]. Boundary-Layer Meteorolo-gy, 2013, 146(3):393-419.
[23] Aumond P, Masson V, Lax C, et al. Including the drag effects of cano-pies:Real case large-eddy simulation studies[J]. Boundary-Layer Me-teorology, 2013, 146(1):65-80.
[24] Shaw R H, Schumann U. Large-eddy simulation of turbulent flow above and within a forest[J]. Boundary-Layer Meteorology, 1992, 61(1):47-64.
[25] Raupach M R, Finnigan J J, Brunet Y. Coherent eddies and turbu-lence in vegetation canopies:The mixing-layer analogy[J]. BoundaryLayer Meteorology, 1996, 78(3):351-382.
[26] Miao S G, Jiang W M. Large eddy simulation of turbulent flow in a for-est canopy and the forest boundary layer[J]. Chinese Journal of Geo-physics, 2004, 47(4):682-690.
[27] Dupont S, Brunet Y. Influence of foliar density profile on canopy flow:A large-eddy simulation study[J]. Agricultural and Forest Meteorology, 2008, 148(6):976-990.
[28] Huang J, Cassiani M, Albertson J D. The effects of vegetation density on coherent turbulent structures within the canopy sublayer:A largeeddy simulation study[J]. Boundary-Layer Meteorology, 2009, 133(2):253-275.
[29] Schlegel F, Stiller J, Bienert A, et al. Large-eddy simulation of inho-mogeneous canopy flows using high resolution terrestrial laser scan-ning data[J]. Boundary-Layer Meteorology, 2012, 142(2):223-243.
[30] Schlegel F, Stiller J, Bienert A, et al. Large-eddy simulation study of the effects on flow of a heterogeneous forest at sub-tree resolution[J]. Boundary-Layer Meteorology, 2015, 154(1):27-56.
[31] Bailey B, Stoll R. Turbulence in sparse, organized vegetative canopies:A large-eddy simulation study[J]. Boundary-Layer Meteorology, 2013, 147(3):369-400.
[32] Cassiani M, Katul G G, Albertson J D. The effects of canopy leaf area index on airflow across forest edges:Large-eddy simulation and analyt-ical results[J]. Boundary-Layer Meteorology, 2008, 126(3):433-460.
[33] Dupont S, Brunet Y. Coherent structures in canopy edge flow:A largeeddy simulation study[J]. Journal of Fluid Mechanics, 2009, 630(13):93-128.
[34] Finnigan J J, Belcher S E. Flow over a hill covered with a plant cano-py[J]. Quarterly Journal of the Royal Meteorological Society, 2004, 130(596):1-29.
[35] Dupont S, Brunet Y, Finnigan J J. Large-eddy simulation of turbulent flow over a forested hill:Validation and coherent structure identifica-tion[J]. Quarterly Journal of the Royal Meteorological Society, 2008, 134(636):1911-1929.
[36] Yue W, Parlange M, Meneveau C, et al. Large-eddy simulation of plant canopy flows using plant-scale representation[J]. Boundary-Lay-er Meteorology, 2007, 124(2):183-203.
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