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IDENTIFICATION AND ELECTROMAGNETIC CONTROL OF STRUCTURES IN RAYLEIGH-BENARD CONVECTION

Jos Verdoold
Department of Multi-Scale Physics, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands

Peter Witte
Department of Multi-Scale Physics, Delft University of Technology P.O. Box 5046, 2600 GA Delft, The Netherlands

Lambertus Hoek
Department of Multi-Scale Physics, Delft University of Technology P.O. Box 5046, 2600 GA Delft, The Netherlands

Mark J. Tummers
Section of Transport Phenomena, Department of Chemical Engineering, Faculty of Applied Sciences Delft University of Technology and J. M. Burgerscentre for Fluid Dynamics Julianalaan, 2628 BL Delft

Kemo Hanjalic
Department of Applied Physics Delft University of Technology 2600 GA Delft, The Netherlands

Résumé

The paper reports on an investigation of turbulent flow structures in a large aspect-ratio (W:H=4:1) Rayleigh-Benard convection cell and their correlation with the instantaneous heat transfer. The final aim of the work is to manipulate these structures by means of electromagnetic (EM) forces that are concentrated in a thin region adjacent to the bottom wall, thus enabling to exert a body force on the fluid in the boundary layer (Verdoold et al., 2003). While many issues are still to be addressed, this abstract reports on some interesting results obtained in absence of the EM forcing. In RB convection the formation of plumes and their impingement is associated with motion in the wall boundary layers, governing the heat transfer. We report on a quantitative investigation of distinct structures and spoke patterns in the temperature field in the vicinity of the boundary layer, which have been visualised earlier by e.g. Theerthan and Arakeri (2000) and others.