The impact of humidity on vortex creation around isolated buildings

The effect of humidity on the climatic conditions and the turbulence around an isolated building has not been yet investigated in literature. This paper analyses the simultaneous effect of architectural and environmental parameters on the vortex creation around a building, focusing on the impact of relative humidity. Sixty-four 3D computational fluid dynamics simulations have been performed, coupling 4 values of inlet velocity, air temperature, solar radiation and building height with 4 values of relative humidity. Results demonstrated that the inclusion of humidity in the simulations has an impact on the vortex creation. Differences in values and trends of the vortex dimensions (Hc, Xc, and Lc) were obtained compared to previous studies where relative humidity was not considered. The highest percentage difference between the two studies regards the building height, where the addition of relative humidity made the Xc value decrease by up to 56%. Among the analysed environmental parameters, building height has the higher impact on the characteristics of the vortex, followed by air velocity. The results have been compared with the analytic formula of the ASHRAE Handbook. Cubic mathematical equations have been developed correlating the vortex dimensions with building height, air velocity and relative humidity.