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Linear stability of Hill’s vortex to axisymmetric perturbations

Published online by Cambridge University Press:  28 June 2016

Bartosz Protas*
Affiliation:
Department of Mathematics and Statistics, McMaster University, Hamilton, ON L8S 4K1, Canada
Alan Elcrat
Affiliation:
Department of Mathematics, Wichita State University, Wichita, KS 67260, USA
*
Email address for correspondence: [email protected]

Abstract

We consider the linear stability of Hill’s vortex with respect to axisymmetric perturbations. Given that Hill’s vortex is a solution of a free-boundary problem, this stability analysis is performed by applying methods of shape differentiation to the contour dynamics formulation of the problem in a three-dimensional axisymmetric geometry. This approach allows us to systematically account for the effect of boundary deformations on the linearized evolution of the vortex under the constraint of constant circulation. The resulting singular integro-differential operator defined on the vortex boundary is discretized with a highly accurate spectral approach. This operator has two unstable and two stable eigenvalues complemented by a continuous spectrum of neutrally stable eigenvalues. By considering a family of suitably regularized (smoothed) eigenvalue problems solved with a range of numerical resolutions, we demonstrate that the corresponding eigenfunctions are in fact singular objects in the form of infinitely sharp peaks localized at the front and rear stagnation points. These findings thus refine the results of the classical analysis by Moffatt & Moore (J. Fluid Mech., vol. 87, 1978, pp. 749–760).

Type
Papers
Copyright
© 2016 Cambridge University Press 

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References

Baker, G. R. 1990 A study of the numerical stability of the method of contour dynamics. Phil. Trans. R. Soc. Lond. A 333, 391400.Google Scholar
Bliss, D. B.1973 The dynamics of flows with high concentrations of vorticity. PhD thesis, Department of Aeronautics and Astronautics, Massachusetts Institute of Technology.Google Scholar
Delfour, M. C. & Zolésio, J.-P. 2001 Shape and Geometries – Analysis, Differential Calculus and Optimization. SIAM.Google Scholar
Drazin, P. G. & Reid, W. H. 2004 Hydrodynamic Stability, 2nd edn. Cambridge University Press.CrossRefGoogle Scholar
Driscoll, T. A., Hale, N. & Trefethen, L. N.(Eds) 2014 Chebfun Guide, 1st edn. Pafnuty Publications.Google Scholar
Dritschel, D. G. 1985 The stability and energetics of corotating uniform vortices. J. Fluid Mech. 157, 95134.Google Scholar
Dritschel, D. G. 1988 Nonlinear stability bounds for inviscid, two-dimensional, parallel or circular flows with monotonic vorticity, and the analogous three-dimensional quasi-geostrophic flows. J. Fluid Mech. 191, 575581.Google Scholar
Dritschel, D. G. 1990 The stability of elliptical vortices in an external straining flow. J. Fluid Mech. 210, 223261.Google Scholar
Dritschel, D. G. 1995 A general theory for two-dimensional vortex interactions. J. Fluid Mech. 293, 269303.CrossRefGoogle Scholar
Dritschel, D. G. & Legras, B. 1991 The elliptical models of two-dimensional vortex dynamics. II: Disturbance equations. Phys. Fluids A 3, 855869.Google Scholar
Elcrat, A., Fornberg, B. & Miller, K. 2005 Stability of vortices in equilibrium with a cylinder. J. Fluid Mech. 544, 5368.Google Scholar
Elcrat, A. & Protas, B. 2013 A framework for linear stability analysis of finite-area vortices. Proc. R. Soc. Lond. A 469, 20120709.Google Scholar
Fraenkel, L. E. 1972 Examples of steady vortex rings of small cross–section in an ideal fluid. J. Fluid Mech. 51, 119135.Google Scholar
Fukumoto, Y. & Moffatt, H. K. 2008 Kinematic variational principle for motion of vortex rings. Physica D 237, 22102217.Google Scholar
Fukuyu, A., Ruzi, T. & Kanai, A. 1994 The response of Hill’s vortex to a small three dimensional disturbance. J. Phys. Soc. Japan 63, 510527.CrossRefGoogle Scholar
Guo, Y., Hallstrom, Ch. & Spirn, D. 2004 Dynamics near an unstable Kirchhoff ellipse. Commun. Math. Phys. 245, 297354.Google Scholar
Hackbusch, W. 1995 Integral Equations: Theory and Numerical Treatment. Birkhäuser.Google Scholar
Hattori, Y. & Hijiya, K. 2010 Short-wavelength stability analysis of Hill’s vortex with/without swirl. Phys. Fluids 22, 074104.CrossRefGoogle Scholar
Hill, M. J. M. 1894 On a spherical vortex. Phil. Trans. R. Soc. Lond. A 185, 213245.Google Scholar
Kamm, J. R.1987 Shape and stability of two–dimensional vortex regions. PhD thesis, Caltech.Google Scholar
Kelvin, Lord 1880 Vibrations of a columnar vortex. Phil. Mag. 10, 155168.Google Scholar
Laub, A. J. 2005 Matrix Analysis for Scientists and Engineers. SIAM.Google Scholar
Lifschitz, A. 1995 Instabilities of ideal fluids and related topics. Z. Angew. Math. Mech. 75, 411.Google Scholar
Lifschitz, A. & Hameiri, E. 1991 Local stability conditions in fluid dynamics. Phys. Fluids A 3, 26442651.CrossRefGoogle Scholar
Llewellyn Smith, S. G. & Ford, R. 2001 Three-dimensional acoustic scattering by vortical flows. Part I: General theory. Phys. Fluids 13, 28762889.Google Scholar
Love, A. E. H. 1893 On the stability of certain vortex motions. Proc. Lond. Math. Soc. s1‐25, 1843.Google Scholar
Luzzatto-Fegiz, P. & Williamson, C. H. K. 2010 Stability of conservative flows and new steady-fluid solutions from bifurcation diagrams exploiting variational argument. Phys. Rev. Lett. 104, 044504.CrossRefGoogle ScholarPubMed
Luzzatto-Fegiz, P. & Williamson, C. H. K. 2012 Determining the stability of steady two-dimensional flows through imperfect velocity–impulse diagrams. J. Fluid Mech. 706, 323350.Google Scholar
Mitchell, T. B. & Rossi, L. F. 2008 The evolution of Kirchhoff elliptic vortices. Phys. Fluids 20, 054103.Google Scholar
Moffatt, H. K. 1969 The degree of knottedness of tangled vortex lines. J. Fluid Mech. 35, 117129.Google Scholar
Moffatt, H. K. & Moore, D. W. 1978 The response of Hill’s spherical vortex to a small axisymmetric disturbance. J. Fluid Mech. 87, 749760.Google Scholar
Mohseni, K. 2001 Statistical equilibrium theory for axisymmetric flow: Kelvin’s variational principle and an explanation for the vortex ring pinch-off process. Phys. Fluids 13, 1924.Google Scholar
Moore, D. W. & Saffman, P. G. 1971 Structure of a line vortex in an imposed strain. In Aircraft Wake Turbulence and Its Detection (ed. Olsen, J. H., Goldburg, A. & Rogers, M.), pp. 339354. Plenum.Google Scholar
Norbury, J. 1973 A family of steady vortex rings. J. Fluid Mech. 57, 417431.Google Scholar
Olver, F. W. J., Lozier, D. W., Boisvert, R. F. & Clark, C. W. 2010 NIST Handbook of Mathematical Functions. Cambridge University Press.Google Scholar
Pozrikidis, C. 1986 The nonlinear instability of Hill’s vortex. J. Fluid Mech. 168, 337367.Google Scholar
Pullin, D. I. 1992 Contour dynamics methods. Annu. Rev. Fluid Mech. 24, 89115.CrossRefGoogle Scholar
Rozi, T. 1999 Evolution of the surface of Hill’s vortex subjected to a small three-dimensional disturbance for the cases of m = 0, 2, 3 and 4. J. Phys. Soc. Japan 68, 2940.Google Scholar
Rozi, T. & Fukumoto, Y. 2000 The most unstable perturbation of wave-packet form inside Hill’s vortex. J. Phys. Soc. Japan 69, 27002701.Google Scholar
Saffman, P. G. 1992 Vortex Dynamics. Cambridge University Press.Google Scholar
Saffman, P. G. & Szeto, R. 1980 Equilibrium shapes of a pair of equal uniform vortices. Phys. Fluids 23, 23392342.Google Scholar
Schmid, P. J. & Hennigson, D. S. 2001 Stability and Transition in Shear Flows. Springer.Google Scholar
Shariff, K., Leonard, A. & Ferziger, J. H. 2008 A contour dynamics algorithm for axisymmetric flow. J. Comput. Phys. 227, 90449062.Google Scholar
Wakelin, S. L. & Riley, N. 1996 Vortex ring interactions. II: Inviscid models. Q. J. Mech. Appl. Maths 49, 287309.CrossRefGoogle Scholar
Weinstein, M. I. 2006 Extended Hamiltonian systems. In Handbook of Dynamical Systems (ed. Hasselblatt, B. & Katok, A.), vol. 1B. North-Holland.Google Scholar
Wu, H. M. II, Overman, E. A. & Zabusky, N. J. 1984 Steady-state solutions of the Euler equations in two dimensions: rotating and translating V-states and limiting cases. I: numerical algorithms and results. J. Comput. Phys. 53, 4271.Google Scholar
Wu, J.-Z., Ma, H.-Y. & Zhou, M.-D. 2006 Vorticity and Vortex Dynamics. Springer.Google Scholar