摘要

A Rayleigh-Benard problem (RB) describes thermally driven flow against gravity between two heated plates. The fluid is accelerated by local density differences and a resulting pressure gradient. Directly at the heated walls the temperature distribution is determinate by increasing temperature gradients. In the centre region convective mass exchange is dominant. Density changes due to temperature differences are considered in the Large Eddy simulation by a compressible coupled model. Previous work investigates similar setups with a Boussinesq-approximation [9, 10]. The investigated Rayleigh-numbers lie between 6 · 10⁷ and 4 · 10⁸. A direct correlation between Rayleigh- and Nusselt-number is observed. The temperature profile shows an asymmetry, which is explainable according to the density weighted velocity profile. [1] also detects an asymmetry in the temperature profile of water for a RB with non-boussinesq effects. Simulation results are compared with analytical model results [4, 5] and experimental data [2].