Abstract
This paper presents laboratory experiments of aerodynamically fully rough, neutral flow over a series of sinusoidal hills. Two sets of hills, with maximum gradients (slopes) of 0.2 (10°) and 0.4 (20°), were considered.The flow remained attached in the former case while separation occurredin the latter. Characteristics of the mean flow and turbulence statistics are discussed and compared with profiles over a flat surface covered with the same roughness as the hills. Comparisons are made with linear theory predictions for the flow in the inner region and aloft. Accurate measurements of the surface pressure were also made, enabling the comparison between the measured pressure drag and predictions from theoretical and computational work with different turbulent closure schemes. Organised secondary flow in the spanwise direction, observed previously in both experimental and computational studies, was also observed here over the small hills.
Similar content being viewed by others
References
Belcher, S. E., Newle T. M. J., and Hunt, J. C. R.: 1993, ‘The Drag on an Undulating Surface Induced by the Flow of a Turbulent Boundary Layer’ J. Fluid Mech. 249, 557-596.
Bradbury, L. J. S. and Castro, I. P.: 1971, ‘A Pulsed-Wire Technique for Velocity Measurements in Highly Turbulent Flows’ J. Fluid Mech. 49, 657-691.
Britter, R. E., Hunt, J. C. R., and Richards, K. J.: 1981, ‘Air Flow over a Two Dimensional Hill: Studies of Velocity Speed Up, Roughness Effects and Turbulence’ Quart. J. Roy. Meteorol. Soc. 107, 91-110.
Finnigan, J. J., Raupach M. R., Bradley, E. F., and Aldis, G. K.: 1990, ‘A Wind Tunnel Study of Turbulent Flow over a Two-Dimensional Ridge’ Boundary-Layer Meteorol. 50, 277-317.
Gong, W. and Ibbetson, A.: 1989, ‘A Wind Tunnel Study of Turbulent Flow over Model Hills’ Boundary-Layer Meteorol. 49, 113-148.
Gong, W., Taylor, P. A., and Dörnbrack A.: 1996, ‘Turbulent Boundary Layer Flow over Fixed Aerodynamically Rough Two Dimensional Sinusoidal Waves’ J. Fluid Mech. 312, 1-37.
Grant, A. L. M.: 1992, ‘The Structure of Turbulence in the Near-Neutral Atmospheric Boundary Layer’ J. Atmos. Sci. 49, 226-239.
Grant, A. L. M. and Mason, P. J.: 1990, ‘Observations of Boundary Layer Structure over Complex Terrain’ Quart. J. Roy. Meteorol. Soc. 116, 159-186.
Hunt, J. C. R., Leibovich, S., and Richards, K. J.: 1988, ‘Turbulent Shear Flows over a Low Hills’ Quart. J. Roy. Meteorol. Soc. 114, 1435-1471.
Jackson, P. S. and Hunt, J. C. R.: 1975, ‘Turbulent Wind Flow over a Low Hill’ Quart. J. Roy. Meteorol. Soc. 101, 929-955.
Jenkins, G. J., Mason, P. J., Moores,W. H., and Sykes, R. I.: 1981, ‘Measurements of the Flow Structure Around Ailsa Craig, a Steep, Three Dimensional, Isolated Hill’ Quart. J. Roy. Meteorol. Soc. 107, 833-851.
Khurshudyan, L. H., Snyder, W. H., and Nekrasov, I. V.: 1981, Flow and Dispersion of Pollutants over Two Dimensional Hills, Env. Prot. Agency Rpt. No. EPA-600/4-81-067, Research Triangle Park, NC, 130 pp.
Mason, P. J. and King, J. C.: 1984, ‘Atmospheric Flow over a Succession of Nearly Two Dimensional Ridges and Valleys’ Quart. J. Roy. Meteorol. Soc. 110, 821-845.
Mason, P. J. and King, J. C.: 1985, ‘Measurements and Predictions of Flow and Turbulence over an Isolated Hill of Moderate Slope’ Quart. J. Roy. Meteorol. Soc. 111, 617-640.
Mason, P. J. and Sykes, R. I.: 1979, ‘Flow over an Isolated Hill of Moderate Slope’ Quart. J. Roy. Meteorol. Soc. 105, 383-395.
Miller, C. A.: 1995, Turbulent Boundary Layers above Complex Terrain, Ph.D. Thesis, University of Western Ontario, U.S.A., 236 pp.
Newley, T. J.: 1985, Turbulent Airflow over Hills, Ph.D. Thesis, University of Cambridge, U.K., 394 pp.
Phillips, W. R. C. and Wu, Z.: 1994, ‘On the Instability of Wave-Catalysed Longitudinal Vortices in Strong Shear’ J. Fluid Mech. 272, 235-254.
Phillips, W. R. C., Wu, Z., and Lumley, J. L.: 1996, ‘On the Formation of Longitudinal Vortices in a Turbulent Boundary Layer over Wavy Terrain’ J. Fluid Mech. 326, 321-341.
Salmon, J. R., Teunissen, H. W., Mickle, R. E., and Taylor, P. A.: 1988, ‘The Kettles Hill Project: Field Observations, Wind-Tunnel Simulations and Numerical Model Predictions for Flow over a Low Hill’ Boundary-Layer Meteorol. 43, 309-343.
Stull, R. B.: 1993, ‘An Introduction to Boundary Layer Meteorology’ Kluwer Academic Publishers, Dordrecht, 666 pp.
Sutton, O. G.: 1953, Micrometeorology, McGraw Hill, 333 pp.
Sykes, R. I.: 1980, ‘An Asymptotic Theory of Incompressible Turbulent Boundary Layer Flow over a Small Hump’ J. Fluid Mech. 101, 647-670.
Taylor, P. A.: 1981, ‘Model Predictions of Neutrally Stratified Planetary Boundary Layer Flow over Ridges’ Quart. J. Roy. Meteorol. Soc. 107, 111-120.
Taylor, P. A. and Teunissen H. W.: 1987, ‘The Askervein Hill Project: Overview and Background Data’ Boundary-Layer Meteorol. 39, 15-39.
Wood, N.: 1992, Turbulent Flow over Three Dimensional Hills, Ph.D. Thesis, University of Reading, U.K., 223 pp.
Wood, N.: 1995, ‘The Onset of Separation in Neutral, Turbulent Flow over Hills’ Boundary-Layer Meteorol. 76, 137-164.
Wood, N. and Mason, P. J.: 1993, ‘The Pressure Force Induced by Neutral, Turbulent Flow over Hills’ Quart. J. Roy. Meteorol. Soc. 119, 1233-1267.
Xu, D., Ayotte, K. W., and Taylor, P. A.: 1994, ‘Development of a Non-Linear Mixed Spectral Finite Model for Turbulent Boundary-Layer Flow over Topography’ Boundary-Layer Meteorol. 70, 341-367.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Athanassiadou, M., Castro, I.P. Neutral Flow Over A Series Of Rough Hills: A Laboratory Experiment. Boundary-Layer Meteorology 101, 1–30 (2001). https://doi.org/10.1023/A:1019250801054
Issue Date:
DOI: https://doi.org/10.1023/A:1019250801054