Turbulent thermal convection at very high Rayleigh numbers
|Principal Investigator(s)||Prof.Dr. Detlef Lohse|
Turbulent convection of a fluid contained between two parallel plates and heated from below, known as Rayleigh-Bénard convection, continues to be a topic of intense research. For given aspect ratio Γ = D/L (D is the cell diameter and L its height) and given geometry, Rayleigh-Bénard convection is determined by the Rayleigh number (measure of the temperature difference) and the Prandtl number (fluid property). The problem is studied both experimentally and with simulations, since both methods are complementary. In experiments it is not possible to accurately measure the heat transfer, while determining the flow field at the same time. This is possible in simulations where one has full access to the complete flow field while the heat transfer properties can be determined. However, due to the fine mesh necessary to accurately resolve the flow, the Rayleigh number that can be obtained in simulations is limited. The agreement between results obtained from experiments and simulations is very good once the resolution of the simulation is sufficient. This allowed results from simulations to be used to clarify important experimental issues. At higher Ra numbers than currently have been reached by high resolution simulations the experimental data start to deviate. Therefore high resolution simulations for these higher Ra numbers needed. The simulation results will be compared with the existing experimental data and can help in explaining deviations found in experimental data.