Wind-Tunnel Study Of Atmospheric Stable Boundary Layers Over A Rough Surface
Tóm tắt
Wind-tunnel simulations of theatmospheric stable boundary layer (SBL) developedover a rough surface were conducted by using athermally stratified wind tunnel at the Research Institutefor Applied Mechanics (RIAM), Kyushu University. Thepresent experiment is a continuation of the workcarried out in a wind tunnel at Colorado StateUniversity (CSU), where the SBL flows were developed over asmooth surface. Stably stratified flows were createdby heating the wind-tunnel airflow to a temperature ofabout 40–50°and by cooling the test-section floor toa temperature of about 10°. To simulate therough surface, a chain roughness was placed over thetest-section floor. We have investigated the buoyancyeffect on the turbulent boundary layer developed overthis rough surface for a wide range of stability,particularly focusing on the turbulence structure andtransport process in the very stable boundary layer.The present experimental results broadly confirm theresults obtained in the CSU experiment with the smoothsurface, and emphasizes the following features: thevertical profiles of turbulence statistics exhibitdifferent behaviour in two distinct stability regimes with weak and strong stability,corresponding to the difference in the verticalprofiles of the local Richardson number. The tworegimes are separated by the critical Richardsonnumber. The magnitudes in turbulence intensities andturbulent fluxes for the weak stability regime aremuch greater than those of the CSU experiments becauseof the greater surface roughness. For the very stableboundary layer, the turbulent fluxes of momentum andheat tend to vanish and wave-like motions due to theKelvin–Helmholtz instability and the rolling up andbreaking of those waves can be observed. Furthermore,the appearance of internal gravity waves is suggestedfrom cross-spectrum analyses.
Tài liệu tham khảo
Andre, J. C. and Mahrt, L.: 1982, ‘The Nocturnal Surface Inversion and Influence of Clear-Air Radiative Cooling’, J. Atmos. Sci. 39, 864–878.
Arya, S. P. S.: 1975, ‘Buoyancy Effects in a Horizontal Flat-Plate Boundary Layer’, J. Fluid Mech. 68, 321–343.
Arya, S. P. S. and Plate, E. J.: 1969, ‘Modeling of the Stably Stratified Atmospheric Boundary Layer’, J. Atmos. Sci. 26, 656–665.
Caughey, S. J.: 1982, ‘Observed Characteristics of the Atmospheric Boundary Layer’, in F. T. M. Nieuwstadt and H. van Dop (eds.), Atmospheric Turbulence and Air Pollution Modelling, D. Reidel Pub. Co., Boston, pp. 107–158.
Caughey, S. J. and Readings, C. J.: 1975, ‘An Observation of Waves and Turbulence in the Earth's Boundary Layer’, Boundary-Layer Meteorol. 9, 279–296.
Caughey, S. J., Wyngaard, J. C., and Kaimal, J. C.: 1979, ‘Turbulence in the Evolving Stable Boundary Layer’, J. Atmos. Sci. 36, 1041–1052.
Coulter, R. L.: 1990, ‘A Case Study of Tutrbulence in the Stable Nocturnal Boundary Layer’, Boundary-Layer Meteorol. 52, 75–91.
De Baas, A. F. and Driedonks, A. G. M.: 1985, ‘Internal Gravity Waves in a Stably Stratified Boundary Layer’, Boundary-Layer Meteorol. 31, 303–323.
Derbyshire, S. H.: 1990, ‘Nieuwstadt's Stable Boundary Layer Revisited’, Quart. J. Roy. Meteorol. Soc. 116, 127–158.
Derbyshire, S. H.: 1995, ‘Stable Boundary Layers: Observations, Models and Variability. Part I: Modelling and Measurements’, Boundary-Layer Meteorol. 74, 19–54.
Finnigan, J. J. and Einaudi, F.: 1981, ‘The Interaction between an Internal Gravity Wave and the Planetary Boundary Layer. Part II: Effect of the Wave on the Turbulence Structure’, Quart. J. Roy. Meteorol. Soc. 107, 807–832.
Finnigan, J. J., Einaudi, F., and Fua, D.: 1984, ‘The Interaction between an Internal Gravity Wave and Turbulence in Stably-Stratified Nocturnal Boundary Layer’, J. Atmos. Sci. 41, 2409–2436.
Garratt, J. R.: 1982, ‘Observations in the Nocturnal Boundary Layer’, Boundary-Layer Meteorol. 22, 21–48.
Hanazaki, H. and Hunt, J. C. R.: 1996, ‘Linear Processes in Unsteady Stably Stratified Turbulence’, J. Fluid Mech. 318, 303–337.
Holtslag, A. A. M. and Nieuwstadt, F. T. M.: 1986, ‘Scaling the Atmospheric Boundary Layer’, Boundary-Layer Meteorol. 36, 201–209.
Hunt, J. C. R., Kaimal, J. C., and Gaynor, J. E.: 1985, ‘Some Observations of Turbulence Structure in Stable Layers’, Quart. J. Roy. Meteorol. Soc. 111, 793–815.
Komori, S. and Nagata, K.: 1996, ‘Effects ofMolecular Diffusivities on Counter-Gradient Scalar and Momentum Transfer in Strongly Stable Stratification’, J. Fluid Mech. 326, 205–237.
Komori, S., Ueda, H., Ogino, F., and Mizushima, T.: 1983, ‘Turbulence Structure in Stably Stratified Open-Channel Flow’, J. Fluid Mech. 130, 13–26.
Kondo, J., Kanechika, O., and Yasuda, N.: 1978, ‘Heat and Momentum Transfers under Strong Stability in the Atmospheric Surface Layer’, J. Atmos. Sci. 35, 1012–1021.
Lenschow, D. H., Li, X. S., Zhu, C. J., and Stankov, B. B.: 1988, ‘The Stably Stratified Boundary Layer over the Great Plains’, Boundary-Layer Meteorol. 42, 195–121.
Lienhard V. J. H. and Van Atta, C.W.: 1990, ‘The Decay of Turbulence in Thermally Stratified Flow’, J. Fluid Mech. 210, 57–112.
Mahrt, L.: 1985, ‘Vertical Structure and Turbulence in the Very Stable Boundary Layer’, J. Atmos. Sci. 42, 2333–2349.
Mahrt, L.: 1999, ‘Stratified Atmospheric Boundary Layers’, Boundary-Layer Meteorol. 90, 375–396.
Mahrt, L., Heald, R. C., Lenschow, D. H., Stankov, B. B., and Troen, I. B.: 1979, ‘An Observational Study of the Structure of the Nocturnal Boundary Layer’, Boundary-Layer Meteorol. 17, 247–264.
Mahrt, L., Sun, J., Blumen, W., Delany, T., and Oncley, S.: 1998, ‘Nocturnal Boundary-Layer Regimes’, Boundary-Layer Meteorol. 88, 255–278.
Meroney, R. N.: 1990, ‘Fluid dynamics of Flow over Hills/Mountains-Insights Obtained through Physical Modeling’, in W. Blumen (ed.), Atmospheric Processes over Complex Terrain, American Meteorological Society, Meteorological Monographs 23(45), pp. 145–171.
Nicholl, C. I. H.: 1970, ‘Some Dynamical Effects of Heat on a Turbulent Boundary Layer’, J. Fluid Mech. 40, 361–384.
Nieuwstadt, F. T. M.: 1984a, ‘The Turbulent Structure of the Stable, Nocturnal Boundary Layer’, J. Atmos. Sci. 41, 2202–2216.
Nieuwstadt, F. T. M.: 1984b, ‘Some Aspects of the Turbulent Stable Boundary Layer’, Boundary-Layer Meteorol. 30, 31–55.
Ogawa, Y., Diosey, P. G., Uehara, K., and Ueda, H.: 1985, ‘Wind Tunnel Observation of Flow and Diffusion under Stable Stratification’, Atmos. Environ. 19, 65–74.
Ohya, Y. and Fukamachi, N.: 1997, ‘Development of a Calibrator for Thermo-Anemometer’, in Proceedings of the 3rd International Conference on Fluid Dynamic Measurement and Its Applications, Beijing, China, pp. 223–226.
Ohya, Y., Neff, D. E., and Meroney, R. N.: 1997, ‘Turbulence Structure in a Stratified Boundary Layer under Stable Conditions’, Boundary-Layer Meteorol. 83, 139–161.
Ohya, Y., Tatuno, M., Nakamura, Y., and Ueda, H.: 1996, ‘A Thermally Stratified Wind Tunnel for Environmental Flow Studies’, Atmos. Environ. 30, 2881–2887.
Piat, J.-F. and Hopfinger, E. J.: 1981, ‘A Boundary Layer Topped by a Density Interface’, J. Fluid Mech. 113, 411–432.
Smedman, A.-S.: 1988,: ‘Observations of a Multi-Level Turbulence Structure in a Very Stable Atmospheric Boundary Layer’, Boundary-Layer Meteorol. 44, 231–253.
Smedman, A.-S., Hogstrom, U., and Bergstrom, H.: 1997, ‘The Turbulence Regime of a Very Stable Marine Airflow with Quasi-Frictional Decoupling’, J. Geophys. Res. 102, 21049–21059.
Sorbjan, Z.: 1988, ‘Structure of the Stably-Stratified Boundary Layer during the SESAME-1979 Experiment’, Boundary-Layer Meteorol. 44, 255–266.
Stillinger, D. C., Helland, K. N., and Van Atta, C. W.: 1983, ‘Experiments on the Transition of Homogeneous Turbulence to Internal Waves in a Stratified Fluid’, J. Fluid Mech. 131, 91–122.
Stull, R. B.: 1988, An Introduction to Boundary Layer Meteorology, Kluwer Academic Publishers, pp. 499–502 and 513 (666 pp.).
Ueda, H., Mitsumoto, S., and Komori, S.: 1981, ‘Buoyancy Effects on the Turbulent Transport Processes in the Lower Atmosphere’, Quart. J. Roy. Meteorol. Soc. 107, 561–578.
Yamamoto, S., Yokoyama, O., and Gamo, M.: 1979, ‘Observational Study of the Turbulent Structure of the Atmospheric Boundary Layer under Stable Conditions’, J. Meteorol. Soc. Japan 57, 423–430.