|Principal Investigator(s)||Luca Biferale|
Rayleigh-Benard (RB) convection the buoyancy of a fluid heated from below is a classical problem in fluid dynamics. From an applied view-point, thermally driven flows are of utmost importance. Examples are thermal convection in the atmosphere, in the oceans, in metal-production processes in Earth`s mantle, in stars, and the reversal of Earth`s magnetic field. In this classical problem, the flow is determined by the container geometry, the material properties of the fluid, and the top-down temperature difference. A fundamental physical question is the dependence of the heat transfer rate for a given temperature difference between the bottom and top plates, for a given fluid, and given geometry. In the last two decades, considerable progress has been achieved in the understanding of global and local properties for the flow organization of turbulent convection through a combination of experimental, numerical and theoretical works. All this was done especially under the approximation due to Oberbeck and Boussinesq, assuming that the transport and expansion coefficients are constant throughout the fluid and that the temperature dependence of the density is linearized in the buoyancy force. This is justified when one tends to restrict the convection regime to sufficiently small intervals of the temperature drops. Much less is known when compressible and/or multi-phase flows are concerned. We propose here to make fully resolved simulations, using a new Lattice Boltzmann Method for Thermal Flows , addressing thermal convection in 3 dimensional compressible non-ideal flows, close and in presence to phase coexistence (boiling). The main goal consist in assessing the effects of droplet condensation/evaporation on the global heat flux and on the multiscale structure of the flow close to the boundary and in the bulk.