Direct numerical simulation of flow in a confined differentially heated cavity at low Prandtl numbers

The paper concerns the direct numerical simulation using a high-order spectral element method for natural convection flow in a differentially heated cavity at three low Prandtl numbers, Pr = 0.021, 0.1 and 0.2 with a constant Grashof number of 1.8 x 108 in all three cases. The simulated cavity is a cube with 6cm side, where all the walls are no-slip walls. We present the most important statistical quantities of turbulent heat transfer, like turbulence kinetic energy and turbulent heat flux. Despite the same Grashof number, the level of turbulence is significantly different, showing that the turbulence in low Prandtl number cases is further excited by natural convection through the buoyancy term in the momentum equation. We also present the power spectral densities in certain monitor points and show the flow is fully turbulent. Our future work concerns support for the experiment under preparation at the von Karman Institute for Fluid Dynamics in the form of uncertainties in boundary conditions, as well as uncertainties due to temperature dependence of material properties.