Boundary layer interaction in plume-based variable-viscosity thermal convection
ثبت نشده
چکیده
Résumé : Nous avons mesuré la fréquence de formation de panaches dans une expérience de convection thermique à Pr >>1. Comme la viscosité du fluide utilisé varie fortement avec la température, les couches limites chaude et froide ont différentes épaisseurs et viscosités. Ceci entraîne des fréquences différentes pour ces couches. Il semblerait qu’il y ait une interaction directe entre les couches limites, par l’intermédiaire des panaches. En particulier, s’il y a une fréquence principale bien définie pour l’apparition de panaches froids, il y a en a plusieurs pour les panaches chauds, dont l’une est celle des panaches froids. Ces mesures suggèrent donc que des « panaches » froids dans le manteau (les pans de croûte plongeant dans les zones de subduction) peuvent indure des panaches chauds.
منابع مشابه
Global Stability for Thermal Convection in a Couple Stress Fluid Saturating a Porous Medium with Temperature-Pressure Dependent Viscosity: Galerkin Method
A global nonlinear stability analysis is performed for a couple-stress fluid layer heated from below saturating a porous medium with temperature-pressure dependent viscosity for different conducting boundary systems. Here, the global nonlinear stability threshold for convection is exactly the same as the linear instability boundary. This optimal result is important because it shows that lineari...
متن کاملThe Relation Between Mantle Dynamics and Plate Tectonics: A Primer
We present an overview of the relation between mantle dynamics and plate tectonics, adopting the perspective that the plates are the surface manifestation, i.e., the top thermal boundary layer, of mantle convection. We review how simple convection pertains to plate formation, regarding the aspect ratio of convection cells; the forces that drive convection; and how internal heating and temperatu...
متن کاملEffect of slip and variable thermal boundary conditions on hydromagnetic mixed convection flow and heat transfer from a non-linearly stretching surface
The effect of partial slip and temperature dependent fluid properties on the MHD mixed convection flow from a heated, non-linearly stretching surface in the presence of radiation and non-uniform internal heat generation/absorption is investigated. The velocity of the stretching surface was assumed to vary according to power-law form. Thermal transport is analyzed for two types of non-isothermal...
متن کاملBoundary-layer thickness and instabilities in Bénard convection of a liquid with a temperature-dependent viscosity
New and published experimental measurements of spatial and temporal aspects of variable-viscosity convection are compared with boundary layer models. Viscosity m is assumed to decrease with increasing temperature T so that convection occurs beneath a relatively stagnant layer. Of particular interest to applications involving asymptotically large viscosity variations, is the result that both the...
متن کاملCasson Fluid Flow with Variable Viscosity and Thermal Conductivity along Exponentially Stretching Sheet Embedded in a Thermally Stratified Medium with Exponentially Heat Generation
The motion of temperature dependent viscosity and thermal conductivity of steady incompressible laminar free convective (MHD) non-Newtonian Casson fluid flow over an exponentially stretching surface embedded in a thermally stratified medium are investigated. It is assumed that natural convection is induced by buoyancy and exponentially decaying internal heat generation across the space. The dim...
متن کامل