Large-eddy simulation of thin film evaporation and condensation from a hot plate in enclosure: Second order statistics

Abstract

The archetypal case of a hot and wet plate surrounded by a cold and wet square enclosure is studied. Turbulent natural convection, the water evaporation/condensation, the heat exchange between the air and the enclosing solid bodies are simulated. The large-eddy simulation methodology is adopted in conjunction with a dynamic Lagrangian model for sub-grid scale viscosity and thermal-vapour diffusivities. Two statistical steady state simulations (maximum Ra=5×108) and three transitory drying-process simulations are carried out by deactivating and activating the air-solid heat transfer, respectively. The present work extends the companion study of Cintolesi et al. (2016), where first order statistics of the above mentioned cases were presented. Here, second order statistics are shown: first, the turbulent structures of the thermally uncoupled cases are analysed, along with the velocity root-mean square, the turbulent scalar fluxes and the turbulent kinetic energy budget. A few zones of negative production of turbulent kinetic energy are identified and discussed. The presence of splat and anti-splat events on the enclosure surface is detected and discussed. Subsequently, the evolution of the drying-process simulations is reported: the physical properties of the plate materials lead to different decays of the surface thermal fluctuations.