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Three-dimensional absolute and convective instabilities in mixed convection of a viscoelastic fluid through a porous medium

type de publication      article dans une revue internationale avec comité de lecture
date de publication 2010
auteur(s) Hirata Silvia C; Ouarzazi Mohamed Najib
journal (abréviation) Physics Letters A (Phys Lett)
volume (numéro) 374 (26)
  
pages 2661 – 2666
résumé By using the mathematical formalism of absolute and convective instabilities we study the nature of unstable three-dimensional disturbances of viscoelastic flow convection in a porous medium with horizontal through-flow and vertical temperature gradient. Temporal stability analysis reveals that among three-dimensional (3D) modes the pure down-stream transverse rolls are favored for the onset of convection. In addition, by considering a spatiotemporal stability approach we found that all unstable 3D modes are convectively unstable except the transverse rolls which may experience a transition to absolute instability. The combined influence of through-flow and elastic parameters on the absolute instability threshold, wave number and frequency is then determined, and results are compared to those of a Newtonian fluid.
mots clés Mixed convection; Absolute instability; Viscoelastic fluid; Porous medium
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