MAGISTRI JA/VÕI DOKTORITÖÖ TEEMA
TOPIC FOR MASTER AND/OR DOCTORAL THESIS
Convection in Enclosure
Advisor: Arkadi Berezovski, Ph.D., Senior Researcher at Institute of Cybernetics
Background
The incompressible turbulent convection effort focusses on incompressible fluid models. Examples include Earth's daytime planetary boundary layer and penetrative convection into stably stratified fluid layers in the oceans' mixed layers and at the base of the solar convection zone where effects of compressibility are secondary. Of particular interest is the dynamical impact of the small-scale coherence appearing spontaneously in convection, especially as it generates larger-scale circulations and mean flows. Though these examples are adequately modeled with incompressible fluids, each possesses additional dynamical processes (mitigated by, for example, salinity, magnetic fields, water vapor, etc.) which distinguish them.
Task Description
Our approach is to focus on the essential, unifying features of these flows and to initially disregard the details that make them different. To this end we employ large, direct numerical simulations of idealized flows and explore the dependence on asymptotically large Rayleigh and Taylor numbers (the limit appropriate for the problems motivating us.)
On the image to the right the temperature field for waterconvection in a container 10 times taller than wider is shown. The Rayleigh number (non-dimensional temperature difference) is 1.3 x 10^9. For this and lower Ra, the flow is dominated by a disorganised pattern in which eddies stack on top of other eddies, reducing the overall heat transport through the layer. At higher Ra, the flow organises one large circulation spanning the full containerheight. Both the lower-Ra disorganised state and the higher-Ra organised state exhibit the hard-turbulent relation Nu ~ Ra^2/7 where Nu is the Nusselt number (non-dimensional heat transport).
What Could Be the Task for Master Thesis ?
What Could Be the Task for Doctoral Thesis ?
Key Publications
Asymptotic methods in free convection heat transfer theory, O. G. Martynenko, A. Berezovski and Yu. A. Sokovishin, Minsk, Nauka i Technika, 1979 (in Russian).
Prerequisites
Knowledge in the following topics: Calculus, Linear algebra, Continuum mechanics, Programming skills (languages C, Pascal) is presumed.
Arkadi Berezovski, email:berez@ioc.ee, tel. (2) 620 4164| other topics | IoC home |
08/09/1999 webmaster