Joerg Schumacher Technische Universität Ilmenau We discuss three aspects of the mixing in turbulent Rayleigh-Benard convection on the basis of three-dimensional direct numerical simulations. These are the dynamics in the boundary layers close to the heating and cooling plates and the mean flow circulation patterns in convection cells with large aspect ratios. First results of turbulent convection at very low Prandtl numbers are also presented.