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Barotropic quasi-geostrophic f-plane flow over anisotropic topography

Published online by Cambridge University Press:  26 April 2006

G. F. Carnevale ,
R. Purini ,
P. Orlandi  and
P. Cavazza
G. F. Carnevale
Affiliation:
Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, USA
R. Purini
Affiliation:
Istituto di Fisica dell'Atmosfera, P.le Luigi Sturzo 31, 00144 Roma, Italy
P. Orlandi
Affiliation:
Dipartimento di Meccanica e Aeronautica, Universita di Roma, “La Sapienza,” Via Eudossiana 16, 00184 Roma, Italy
P. Cavazza
Affiliation:
Dipartimento di Meccanica e Aeronautica, Universita di Roma, “La Sapienza,” Via Eudossiana 16, 00184 Roma, Italy
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Abstract

For an anisotropic topographic feature in a large-scale flow, the orientation of the topography with respect to the flow will affect the vorticity production that results from the topography–flow interaction. This in turn affects the amount of form drag that the ambient flow experiences. Numerical simulations and perturbation theory are used to explore these effects of change in topographic orientation. The flow is modelled as a quasi-geostrophic homogeneous fluid on an f-plane. The topography is taken to be a hill of limited extent, with an elliptical cross-section in the horizontal. It is shown that, as a result of a basic asymmetry of the quasi-geostrophic flow, the strength of the form drag depends not only on the magnitude of the angle that the topographic axis makes with the oncoming stream, but also on the sign of this angle. For sufficiently low topography, it is found that a positive angle of attack leads to a stronger form drag than that for the corresponding negative angle. For strong topography, this relation is reversed, with the negative angle then resulting in the stronger form drag.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 285 , 25 February 1995 , pp. 329 - 347
Copyright
© 1995 Cambridge University Press

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References

Bannon, P. R. 1980 Rotating barotropic flow over finite isolated topography. J. Fluid Mech. 101, 281–306.Google Scholar
Bannon, P. R. 1985 Flow acceleration and mountain drag. J. Atmos. Sci. 42, 2445–2453.Google Scholar
Batchelor, G. K. 1967 An Introduction to Fluid Dynamics. Cambridge University Press.Google Scholar
Boyer, D. L. 1971 Rotating flow over long shallow ridges. Geophys. Fluid Dyn. 2, 165–183.Google Scholar
Carnevale, G. F. & Frederiksen, J. S. 1987 Nonlinear stability and statistical mechanics of flow over topography. J. Fluid Mech. 175, 157–181.Google Scholar
Cook, K. H. & Held, I. M. 1992 The stationary response to large-scale oragraphy in a general circulation model and a linear model. J. Atmos. Sci. 49, 525–539.Google Scholar
Hart, J. E. 1979 Barotropic quasi-geostrophic flow over anisotropic mountains. J. Atmos. Sci. 36, 1736–1746.Google Scholar
Huppert, H. E. & Bryan, K. 1976 Topographically generated eddies. Deep-Sea Res. 23, 655–679.Google Scholar
Johnson, E. R. 1978 Trapped vortices in rotating flow. J. Fluid Mech. 86, 209–224.Google Scholar
Merkine, L. & Kalnay-Rivas, E. 1976 Rotating stratified flow over finite isolated topography. J. Atmos. Sci. 33, 908–922.Google Scholar
Orlanski, I. 1976 A simple boundary condition for unbounded hyperbolic flows. J. Comput. Phys. 21, 251–269.Google Scholar
Pedlosky, J. 1987 Geophysical Fluid Dynamics, 2nd Edn. Springer.CrossRefGoogle Scholar
Pierrehumbert, R. T. & Malguzzi, P. 1984 Forced coherent structures and local multiple equilibria in a barotropic atmosphere. J. Atmos. Sci. 41, 246–257.Google Scholar
Verron, J. & Le Provost, C. 1985 A numerical study of quasi-geostrophic flow over isolated topography. J. Fluid Mech. 154, 231–252.Google Scholar