Local heat flux in turbulent Rayleigh-Bénard convection

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Climate prediction and weather forecast, the propagation of pollutants in the atmosphere and the oceans as well as an efficient heating or cooling of indoor rooms are essentially based on numerical models in which a great variety of physical and chemical processes has to be considered. Thermal convection is one of these factors. However, its simulation in highly turbulent flows is still very uncertain nowadays. The applicant intend to study turbulent heat transport up to a Rayleigh number of Ra=10^12 in the world-wide largest convection experiment - the Barrel of Ilmenau. Using both local heat flux probes and infrared camera technology the distribution and the temporal evolution of the local heat flux will be measured in the Rayleigh-Bénard cell of 7.15 m diameter. In particular, it will be studied systematically how this distribution depends on the aspect ratio - the ratio between the lateral and the vertical extent of the cell. It is to be shown whether or not local deviations from the mean heat flux may occur as provided in phenomenological scaling theories.