Numerical investigation on thermal and fluid dynamics behaviors of the exit section effect in inclined ventilated roofs

One of the most important requirements for building performance is energy saving and recovering and they are chased developing new strategies for the reduction of energy consumption, due to the heat flux transmitted through buildings envelopes. This work examines a prototypal ventilated roof numerically using a two-dimensional model in Ansys Fluent. Only a single flap of the roof is analyzed because its structure is geometrically and thermally symmetrical. The objective of this work is to study the thermal and fluid dynamic behaviors of a ventilated roof for different configurations of the exit section of the ventilated channel. The model is evaluated in air flow, considering a k-ϵ turbulence model to give the governing equations. Results are a function of an assigned heat flux on the top wall of the ventilation layer. They are analyzed studying temperature and air velocity distributions. The profiles of wall temperature and air velocity along the cross sections and longitudinal sections of the ventilated layer consider the different effects of the various geometric configurations. The results for different considering configuration detect that the ridge form and the outlet reservoir dimensions do not influence the thermal behavior inside the channel whereas a smaller outlet section determines higher wall temperature and lower air velocity in the channel.