Advertisement

Environmental Fluid Mechanics

, Volume 12, Issue 3, pp 209–225 | Cite as

Physical modeling of complex airflows developing above rural terrains

  • Hrvoje KozmarEmail author
Original Article

Abstract

The rural atmospheric boundary layer (ABL) flow was reproduced in a wind tunnel at three different simulation length scales to investigate possible effects of the simulation length scale on flow characteristics. Performance of truncated vortex generators developed for part-depth ABL wind-tunnel simulations was tested in rural terrain exposure against the full-size Counihan vortex generators. A procedure to design the ABL developing above rural type terrain has been described. The 1:395 and 1:236 simulations were created as full-depth simulations, i.e., wind characteristics throughout an entire ABL were reproduced in the wind tunnel. The 1:208 simulation was a part-depth simulation, i.e., only a lower 70% of the ABL was experimentally modelled. The projected scaled-up ABL thicknesses are 395, 354, and 416 m full-scale in the 1:395, 1:236, and 1:208 simulations, respectively. Experimental results show similar trends in all three configurations not depending on the simulation length scale factor. This clearly indicates a possibility to physically, in the wind tunnel, reproduce the same rural atmospheric airflows at different simulation length scales.

Keywords

Atmospheric boundary layer flow Atmospheric turbulence Rural terrain Wind-tunnel simulation Counihan method Redesigned vortex generators Scale effects 

List of symbols

d

Displacement height

f

Frequency

fmax

Peak frequency in the power spectral density of longitudinal velocity fluctuations

t

Time

u

Absolute velocity in the x-direction

\({\bar{{u}},\bar{{v}},\bar{{w}}}\)

Time averaged mean velocity components in the x-, y-, z-direction, respectively

\({\bar{{u}}_z}\)

Time averaged mean velocity component in the x-direction at height z

\({\bar{{u}}_{\rm ref}}\)

Reference velocity

uτ

Friction velocity

u′, v′, w

Fluctuating velocity components in the x-, y-, z-direction, respectively

x

Distance in the direction of the flow

y

Spanwise distance from the test section centerplane

z

Vertical distance from the wind-tunnel floor

zref

Reference height

z+

Dimensionless height

z0

Aerodynamic surface roughness length

Iu, Iv, Iw

Turbulence intensity in the x-, y-, z-direction, respectively

Je

Jensen number

Lu,x, Lv,x, Lw,x

Integral length scales of turbulence

ReR

Roughness Reynolds number

Ru,x, Rv,x, Rw,x

Correlation coefficients

Su, Sv, Sw

Power spectral density of the longitudinal, lateral, vertical velocity fluctuations, respectively

T

Total record length

α

Power law exponent

δ

Boundary layer thickness

κ

Von Kármán constant

ρ

Air density

σu, σv, σw

Standard deviation of uvw, respectively

τ

Reynolds shear stress

ν

Air viscosity

Subscripts

m

Model scale in the wind tunnel

p

Prototype, full-scale

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    Cleugh HA, Miller JM, Böhm M (1998) Direct mechanical effects of wind on crops. Agrofor Syst 41: 85–112CrossRefGoogle Scholar
  2. 2.
    Kort J (1988) Benefits of windbreaks to field and forage crops. Agric Ecosyst Environ 22(23): 165–190CrossRefGoogle Scholar
  3. 3.
    Komlev AA (1960) Field-protective afforestation and the increase in financial yield of agriculture (in Russian). Selsk Khoz Povolzhya 6(12): 43–45Google Scholar
  4. 4.
    Woodruff NP, Lyles L, Siddoway FH, Fryrear DW (1972) How to control wind erosion. Agric Inf Bulletin 354, USDA-ARS, Washington, p 22Google Scholar
  5. 5.
    Nobel PS (1981) Wind as an ecological factor. In: Physiological plant ecology I: Responses to the physical environment, Encyclopedia of plant physiology new series vol. 12A. Springer-Verlag, Berlin, pp 475–500Google Scholar
  6. 6.
    Van Gardingen P, Grace J (1991) Plants and wind. Adv Bot Res 18: 189–253CrossRefGoogle Scholar
  7. 7.
    Cleugh HA (1998) Effects of windbreaks on airflow, microclimates and crop yields. Agrofor Syst 41: 55–84CrossRefGoogle Scholar
  8. 8.
    Van Eimern J, Karschon R, Razumova LA, Robertson GW (1964) Windbreaks and shelterbelts. World Meteorological Organization, Technical Note No. 59, pp 188Google Scholar
  9. 9.
    Rosenberg NJ (1979) Windbreaks for reducing moisture stress. In: Modification of aerial environment of plants (ASAE). St. Joseph, Michigan, pp 538Google Scholar
  10. 10.
    Wilson J (1985) Numerical studies of flow through a windbreak. J Wind Eng Ind Aerodyn 21: 119–154CrossRefGoogle Scholar
  11. 11.
    Heisler GM, Dewalle DR (1988) Effects of windbreak structure on wind flow. Agric Ecosyst Environ 22–23: 41–69CrossRefGoogle Scholar
  12. 12.
    McNaughton KG (1988) Effects of windbreaks on turbulent transport and microclimate. Agric Ecosyst Environ 22–23: 17–39CrossRefGoogle Scholar
  13. 13.
    Patton EG, Shaw RH, Judd MJ, Raupach MR (1998) Large-eddy simulation of windbreak flow. Boundary-Layer Meteorol 87: 275–306CrossRefGoogle Scholar
  14. 14.
    Wang H, Takle ES (2001) Shelterbelts and windbreaks: mathematical modeling and computer simulations of turbulent flows. Annu Rev Fluid Mech 33: 549–586CrossRefGoogle Scholar
  15. 15.
    Kozmar H (2010) Scale effects in wind tunnel modeling of an urban atmospheric boundary layer. Theor Appl Climatol 100(1–2): 153–162CrossRefGoogle Scholar
  16. 16.
    Kozmar H (2011) Wind-tunnel simulations of the suburban ABL and comparison with international standards. Wind Struct 14(1): 15–34Google Scholar
  17. 17.
    Kozmar H (2011) Characteristics of natural wind simulations in the TUM boundary layer wind tunnel. Theor Appl Climatol. doi: 10.1007/s00704-011-0417-9
  18. 18.
    Counihan J (1969) A method of simulating a neutral atmospheric boundary layer in a wind tunnel. In: AGARD Conference Proceedings 43Google Scholar
  19. 19.
    Counihan J (1969) An improved method of simulating an atmospheric boundary layer in a wind tunnel. Atmos Environ 3: 197–214CrossRefGoogle Scholar
  20. 20.
    Counihan J (1973) Simulation of an adiabatic urban boundary layer in a wind tunnel. Atmos Environ 7: 673–689CrossRefGoogle Scholar
  21. 21.
    Cook NJ (1978) Determination of the model scale factor in wind-tunnel simulations of the adiabatic atmospheric boundary layer. J Wind Eng Ind Aerodyn 2(4): 311–321CrossRefGoogle Scholar
  22. 22.
    Kozmar H. (2011) Truncated vortex generators for part-depth wind-tunnel simulations of the atmospheric boundary layer flow. J Wind Eng Ind Aerodyn 99(2–3): 130–136CrossRefGoogle Scholar
  23. 23.
    Kozmar H, Džijan I, Šavar M (2005) Uniformity of atmospheric boundary layer model in the wind tunnel (in Croatian). Strojarstvo 47(5–6): 157–167Google Scholar
  24. 24.
    Counihan J (1971) Wind tunnel determination of the roughness length as a function of the fetch and the roughness density of three-dimensional roughness elements. Atmos Environ 5: 637–642CrossRefGoogle Scholar
  25. 25.
    Gartshore IS, De Croos KA (1977) Roughness element geometry required for wind tunnel simulations of the atmospheric wind. J Fluids Eng 9: 480–485CrossRefGoogle Scholar
  26. 26.
    Fang C, Sill BL (1992) Aerodynamic roughness length: correlations with roughness elements. J Wind Eng Ind Aerodyn 41–44: 449–460CrossRefGoogle Scholar
  27. 27.
    Varshney K, Poddar K (2011) Experiments on integral length scale control in atmospheric boundary layer wind tunnel. Theor Appl Climatol. doi: 10.1007/s00704-011-0415-y
  28. 28.
    Kozmar H (2008) Influence of spacing between buildings on wind characteristics above rural and suburban areas. Wind Struct 11(5): 413–426Google Scholar
  29. 29.
    Kozmar H (2011) Improved experimental simulation of wind characteristics around tall buildings. J Aerosp Eng. doi: 10.1061/(ASCE)AS.1943-5525.0000167
  30. 30.
    Gromke C, Ruck B (2005) Die Simulation atmosphärischer Grenzschichten in Windkanälen. In: Proceedings of the 13 th GALA Fachtagung: Lasermethoden in der Strömungsmesstechnik. Cottbus, GermanyGoogle Scholar
  31. 31.
    ESDU (1974) Characteristics of atmospheric turbulence near the ground, Part II: Single point data for strong winds (neutral atmosphere). In: Engineering Sciences Data Unit 74031Google Scholar
  32. 32.
    Simiu E, Scanlan RH (1996) Wind effects on structures 3rd edn. Wiley, New YorkGoogle Scholar
  33. 33.
    Hucho W-H (2002) Aerodynamik der stumpfen Körper. Vieweg&Sohn, WiesbadenGoogle Scholar
  34. 34.
    Plate EJ (1982) Wind tunnel modelling of wind effects in engineering. In: Engineering Meteorology. Elsevier, AmsterdamGoogle Scholar
  35. 35.
    Schlichting H, Gersten K (1996) Grenzschicht-Theorie. Springer Verlag, BerlinGoogle Scholar
  36. 36.
    Balendra T, Shah DA, Tey KL, Kong SK (2002) Evaluation of flow characteristics in the NUS-HDB Wind Tunnel. J Wind Eng Ind Aerodyn 90: 675–688CrossRefGoogle Scholar
  37. 37.
    Counihan J (1975) Adiabatic atmospheric boundary layers: a review and analysis of data from the period 1880–1972. Atmos Environ 9: 871–905CrossRefGoogle Scholar
  38. 38.
    Hellman G (1916) article G Hellman (1916) Über die Bewegung der Luft in den untersten Schichten der Atmosphäre. Meteorol Z 34: 273–285Google Scholar
  39. 39.
    Dyrbye C, Hansen S (1997) Wind loads on structures. Wiley, New YorkGoogle Scholar
  40. 40.
    ESDU (1972) Characteristics of wind speed in the lower layers of the atmosphere near the ground: strong winds (neutral atmosphere). In: Engineering Sciences Data Unit 72026Google Scholar
  41. 41.
    Oertel H (2002) Prandtl: Führer durch die Strömungslehre. Vieweg & Sohn, Braunschweig/WiesbadenGoogle Scholar
  42. 42.
    Thuillier RH, Lappe UO (1964) Wind and Temperature Profile Characteristics from Observations on a 1400 ft Tower. J Appl Meteorol 3: 299–306CrossRefGoogle Scholar
  43. 43.
    Garratt JR (1992) The atmospheric boundary layer. Cambridge University Press, New YorkGoogle Scholar
  44. 44.
    Holmes JD (2001) Wind loading of structures. Spon Press, LondonCrossRefGoogle Scholar
  45. 45.
    ESDU (1985) Characteristics of atmospheric turbulence near the ground: Part II: single point data for strong winds (neutral atmosphere). In: Engineering Sciences Data Unit 85020Google Scholar
  46. 46.
    Kolmogorov AN (1941) The local structure of turbulence in incompressible viscous fluid for very large Reynolds numbers. In: Proceedings of the Academy of Sciences of the USSR 30, pp 299–303Google Scholar
  47. 47.
    Von Kármán T (1948) Progress in the statistical theory of turbulence. In: Proceedings of the National Academy of Sciences of the United States of America 34 (11). Washington, DC, pp 530–539Google Scholar
  48. 48.
    Arya SP (1999) Air pollution meteorology and dispersion. Oxford University Press, OxfordGoogle Scholar
  49. 49.
    Farell C, Iyengar AKS (1999) Experiments on the wind tunnel simulation of atmospheric boundary layers. J Wind Eng Ind Aerodyn 79: 11–35CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media B.V. 2011

Authors and Affiliations

  1. 1.Faculty of Mechanical Engineering and Naval ArchitectureUniversity of ZagrebZagrebCroatia

Personalised recommendations