Eddy diffusivity in convective hydromagnetic systems

• Tipo: Artigo em Revista Científica Internacional
• Data: 2007

Autores

Baptista, M (Autor) Outra; Gama, SMA (Autor) FCUP; Zheligovsky, VA (Autor) Outra

Revista

Título: European Physical Journal B

Vol. 60

Páginas: 337-351

ISSN: 1434-6028

Editora: Springer Nature

Indexação

ISI Web of Knowledge - 2 Citações

Scopus - 3 Citações

Classificação Científica

FOS: Ciências exactas e naturais > Física

Outras Informações

ID Authenticus: P-004-5YX

DOI: 10.1140/epjb/e2007-00351-8

Abstract (EN): An eigenvalue equation, for linear instability modes involving large scales in a convective hydromagnetic system, is derived in the framework of multiscale analysis. We consider a horizontal layer with electrically conducting boundaries, kept at fixed temperatures and with free surface boundary conditions for the velocity field; periodicity in horizontal directions is assumed. The steady states must be stable to short (fast) scale perturbations and possess symmetry about the vertical axis, allowing instabilities involving large (slow) scales to develop. We expand the modes and their growth rates in power series in the scale separation parameter and obtain a hierarchy of equations, which are solved numerically. Second order solvability condition yields a closed equation for the leading terms of the asymptotic expansions and respective growth rate, whose origin is in the (combined) eddy diffusivity phenomenon. For about 10% of randomly generated steady convective hydromagnetic regimes, negative eddy diffusivity is found.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 15