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Título del libro: Emerging Topics On Differential Geometry And Graph Theory
Título del capítulo: Application of Hilbert spaces to the stability study of flows on a sphere

Autores UNAM:
IOURI SKIBA SKIBA;
Autores externos:

Idioma:
Inglés
Año de publicación:
2011
Resumen:

The main properties of spherical harmonics and associated Legendre functions arebriefly surveyed. Geographical coordinate maps for the sphere are defined and the well-known theorem about the partition of unity is given which is an important tool in the theory of integration of functions on smooth compact manifolds. Derivatives Ds and ?s of real degree s of smooth functions on the unit sphere are defined, and a family of Hilbert spaces Hs of generalized functions having fractional derivatives on the sphere is introduced. Instead of the modulus of continuity [1-3], in this work, the Hilbert spaces of functions are defined by means of multiplier operators [4-7]. Orthogonal projectors on the subspace Hn of homogeneous spherical polynomials of degree n and on the subspace PN of spherical polynomials of degree n = N are defined. Some structural properties of Hilbert spaces Hs including various embedding theorems are given, and the rate of convergence of Fourier-Laplace series of functions of Hs is estimated. As applications of theoretical results, both the global asymptotic stability and the normal-mode stability of incompressible flows on a rotating sphere are considered. In particular, conditions for the global asymptotic stability of solutions to the barotropic vorticity equation are given, and the spectral approximation (convergence of eigenvalues and eigenvectors of discrete spectral problems) in the numerical normal-mode stability study of nondivergent viscous flows on a rotating sphere is examined. © 2010 Nova Science Publishers, Inc. All rights reserved.


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