Reentrant hexagons in non-Boussinesq convection.

Madruga Sánchez, Santiago; Riecke, Hermann y Pesch, Werner (2006). Reentrant hexagons in non-Boussinesq convection.. "Journal of Fluid Mechanics", v. 548 ; pp. 341-360. ISSN 0022-1120.

Descripción

Título: Reentrant hexagons in non-Boussinesq convection.
Autor/es:
  • Madruga Sánchez, Santiago
  • Riecke, Hermann
  • Pesch, Werner
Tipo de Documento: Artículo
Título de Revista/Publicación: Journal of Fluid Mechanics
Fecha: 2006
Volumen: 548
Materias:
Escuela: E.T.S.I. Aeronáuticos (UPM) [antigua denominación]
Departamento: Fundamentos Matemáticos de la Tecnología Aeronáutica [hasta 2014]
Licencias Creative Commons: Reconocimiento - Sin obra derivada - No comercial

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Resumen

While non-Boussinesq hexagonal convection patterns are known to be stable close to threshold (i.e. for Rayleigh numbers R ? Rc ), it has often been assumed that they are always unstable to rolls for slightly higher Rayleigh numbers. Using the incompressible Navier?Stokes equations for parameters corresponding to water as the working fluid, we perform full numerical stability analyses of hexagons in the strongly nonlinear regime ( ? (R ? Rc )/Rc = O(1)). We find ?re-entrant? behaviour of the hexagons, i.e. as is increased they can lose and regain stability. This can occur for values of as low as = 0.2. We identify two factors contributing to the re-entrance: (i) far above threshold there exists a hexagon attractor even in Boussinesq convection as has been shown recently and (ii) the non-Boussinesq effects increase with . Using direct simulations for circular containers we show that the re-entrant hexagons can prevail even for sidewall conditions that favour convection in the form of competing stable rolls. For sufficiently strong non-Boussinesq effects hexagons even become stable over the whole -range considered, 0 6 6 1.5.

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Identificador DC: http://oa.upm.es/21712/
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Depositado por: Memoria Investigacion
Depositado el: 03 Mar 2014 14:54
Ultima Modificación: 21 Abr 2016 12:26
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