Numerical Simulations Applied to Energy Efficiency for Buildings with Lattice Boltzmann Method

Convective heat transfer coefficients are often arbitrarily fixed in building energy simulations. This study aims to determine the convective heat transfer coefficients on the floor, the walls and the ceiling of a room with underfloor heating. To conduct this study, natural convection induced by the temperature gradient between the bottom and upper walls within square enclosure has been studied. The upper wall is brought to a sinusoidal temperature to represent its daily change. Different Rayleigh number values are considered here. The study has been carried out by solving numerically momentum and energy equations with the Boussinesq approximation. The governing equations have been solved using the Lattice Boltzmann Method. The study has been carried out for Rayleigh numbers in the range 10 ≤ Ra ≤ 106, while Prandtl number and aspect ratio are kept constant at 0.71 and 1, respectively. The numerical results in the form of average Nusselt number and gain of the time-mean Nusselt number, are presented in this study.