Thermal behavior of curved roof buildings exposed to solar radiation and wind flow for various orientations

In this study air flow, solar radiation and heat transfer from a two dimensional curved roof with north-south and east-west faced are determined and results are compared with flat roof for the same size and orientation. Comparison are performed for their corresponding roof surface temperature, and heat flow for several roof rim angles and also for various wind flow velocities, as well as for different wind directions. Turbulence is modeled by RNG k–ε method and solar radiation distribution over the roof is determined based on an appropriate model applicable to hot arid regions of Iran. Solar radiation is calculated based on the summation of beam and diffuse radiation and ground reflected radiation. For certain inside roof temperature, over all heat transfer to the building is determined with day time for various wind flows and arc shapes and results are compared with flat roof. It was found that various wind flow condition over the vaulted roof makes substantial difference on the convection heat transfer coefficient and finally on the rate of heat transfer to the building with respect to flat roof. Based on heat transfer simulation, roof temperature, heat transfer convection coefficient and heat flow though the vault for different roof arrangement and flat roofs have been determined and advantages of specific vault orientation and wind direction are specified.