Hostname: page-component-8448b6f56d-wq2xx Total loading time: 0 Render date: 2024-04-18T23:49:57.773Z Has data issue: false hasContentIssue false

Inertial modes with large azimuthal wavenumbers in an axisymmetric container

Published online by Cambridge University Press:  20 April 2006

W. W. Wood
Affiliation:
Mathematics Department, University of Melbourne, Parkville, Australia, 3052

Abstract

Free oscillations are considered of a fluid rotating with constant angular velocity $\Omega \hat{\rm z}$ in a rigid axisymmetric container. Modes are sought that vary rapidly in an axial (r, z) plane with a length scale O(n−1) times that of the container, where n [Gt ] 1. The azimuthal wavenumber k > 0 is also taken to be large. The modulated wave modes postulated (represented as in (4.1)) prove to have a quiescent zone near the axis. Elsewhere their pressure is of a uniform order of magnitude. Their velocity however is locally magnified by a factor O(n) near the critical circles. It is argued that for k/n [Lt ] 1 the modulated waves eligible as modes in smooth, convex containers are of two kinds; one, which generally occurs for continuous frequency bands, being singular and indeterminate; the other being like the modes in a sphere. Modes of the second kind are determined for eigenfrequencies ω ≃ √2 Ω for containers whose axia lcross-sections are symmetrical about z = 0 and about r = ±z.

Type
Research Article
Copyright
© 1981 Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Arnol'd, V. I. 1965 Mappings of the circumference onto itself. Am. Math. Soc. Transl. 46, 213284.Google Scholar
Barcilon, V. 1968 Axisymmetric inertial oscillations of a rotating ring of fluid. Mathematika 15, 93102.Google Scholar
Bourgin, D. G. & Duffin, R. 1939 The Dirichlet problem for the vibrating string equation. Bull. Am. Math. Soc. 45, 851859.Google Scholar
Bretherton, F. P. 1964 Low frequency oscillations trapped near the equator. Tellus 16, 181185.Google Scholar
Bryan, G. H. 1889 The waves on a rotating liquid spheroid of finite ellipticity. Phil. Trans. Roy. Soc. A 180, 187219.Google Scholar
Buchal, R. N. & Keller, J. B. 1960 Boundary layer problems in diffraction theory. Comm. Pure Appl. Math. 13, 85114.Google Scholar
Busse, F. H. 1970 Thermal instabilities in rapidly rotating systems. J. Fluid Mech. 44, 441460.Google Scholar
Coddington, E. A. & Levinson, N. 1955 Theory of Ordinary Differential Equations. McGraw-Hill.
Franklin, J. N. 1972 Axisymmetric inertial oscillations of a rotating fluid. J. Math. Anal. Applic. 39, 742760.Google Scholar
Greenspan, H. P. 1968 The Theory of Rotating Fluids. Cambridge University Press.
Hough, S. S. 1895 The oscillations of a rotating ellipsoidal shell containing fluid. Phil. Trans. Roy. Soc. A 186, 469506.Google Scholar
John, F. 1941 The Dirichlet problem for a hyperbolic equation. Am. J. Math. 63, 141154.Google Scholar
Keller, J. B. 1958 A geometrical theory of diffraction. Proc. Symp. Appl. Math. 8, 2752.Google Scholar
Keller, J. B. & Rubinow, S. I. 1960 Asymptotic solution of eigenvalue problems. Ann. Phys. 9, 2475.Google Scholar
Kelvin, Lord 1880 Vibrations of a columnar vortex. Phil. Mag. 10, 155168.Google Scholar
Kudlick, M. D. 1966 On transient motions in a contained rotating fluid. Ph.D. thesis, Massachusetts Institute of Technology.
Malkus, W. V. R. 1967 Hydromagnetic planetary waves. J. Fluid Mech. 28, 793802.Google Scholar
Poincaré, H. 1885 Sur l’équilibre d'une masse fluide animée d'un mouvement de rotation. Acta Mathematica 7, 259380.Google Scholar
Poincaré, H. 1910 Sur la précession des corps déformables. Bull. Astronomique 27, 321356.Google Scholar
Rayleigh, Lord 1910 The problem of the whispering gallery. Phil. Mag. 20 (6), 10011004.Google Scholar
Roberts, P. H. 1968 On the thermal instability of a rotating fluid sphere containing heat sources. Phil. Trans. Roy. Soc. A 263, 93117.Google Scholar
Schaeffer, D. G. 1975 On the existence of discrete frequencies of oscillation in a rotating fluid. Stud. Appl. Math. 54, 269273.Google Scholar
Stewartson, K. 1971 On trapped oscillations of a rotating-fluid in a thin spherical shell: I. Tellus 23, 506510.Google Scholar
Stewartson, K. 1972 On trapped oscillations of a rotating-fluid in a thin spherical shell: II. Tellus 24, 283287.Google Scholar
Stewartson, K. & Rickard, J. A. 1969 Pathological oscillations of a rotating fluid. J. Fluid Mech. 35, 759773.Google Scholar
Stewartson, K. & Walton, I. C. 1976 On waves in a thin shell of stratified rotating fluid. Proc. Roy. Soc. A 349, 141156.Google Scholar
Thorne, R. C. 1957 The asymptotic expansion of Legendre functions of large degree and order. Phil. Trans. Roy. Soc. A 249, 597620.Google Scholar
Walton, I. C. 1975 On waves in a thin rotating spherical shell of slightly viscous fluid. Mathematika, 22, 4659.Google Scholar
Wood, W. W. 1977a A note on the westward drift of the earth's magnetic field. J. Fluid Mech. 82, 389400.Google Scholar
Wood, W. W. 1977b Inertial oscillations in a rigid axisymmetric container. Proc. Roy. Soc. A 358, 1730.Google Scholar