Effect of inertia in Rayleigh-Bénard convection.

We have investigated the influence of the Prandtl number on the dynamics of high Rayleigh number thermal convection. A numerical parameter study in a three-dimensional Rayleigh-Bénard configuration was carried out, where we varied the Prandtl number between 10(-3)< or =Pr< or =10(2). The Rayleigh number was fixed at a value of Ra=10(6). Our main focus lay on the question how the value of the Prandtl number affects the spatial structure of the flow. We investigated the functional dependence of the Nusselt number and the Reynolds number and compared our results with a recent theoretical approach of Grossmann and Lohse [J. Fluid Mech. 407, 27 (2000); Phys. Rev. Lett. 86, 3316 (2001)].