A Numerical Study of Turbulent Thermal Convection in a Cavity with Evaporation at the Free Surface

Evaporation from an air-water interface is controlled by interfacial temperature and hence vapour pressure, but influenced also by gas and water side convection and the means of heat addition. Currently however, our understanding of the effect of turbulence on evaporation rate at a free surface heated from below is far from complete.

The problem in hand is described by the low-Mach number equations for a two-phase system with heat and mass transfer under non-Boussinesq conditions. In the first part of our talk we outline the algorithm for the numerical treatment for these equations based on the Volume-of-Fluid method with a novel scheme taking into account evaporation at the free surface.

In the second part of the talk, we present and discuss results from Large-Eddy Simulations over a range of Rayleigh numbers. Emphasis is placed on the analysis of the emerging turbulent structures and simulations are compared against experimental results. Our presentation concludes with a discussion on the effect of water-side turbulence on evaporation.