Designing the city according to the wind: using a CFD to minimize the impacts of city growth on natural ventilation

This research studies the influence of changing patterns of land use on natural ventilation using a cfd tool, with a case study in Fortaleza, Ceará, Brazil. This urban area is intensifying its occupation through tall buildings and constructive densification. Virtual three-dimensional models were reproduced. The first model represents the present situation of this part of the city, the second one expresses the maximum occupancy permitted by urban legislation and a third scenario indicates an intermediate proposal as a criticism of law permissiveness. These models were submitted to the ANSYS CFX 5.6 fluid dynamics software to simulate the airflow. 39 comparison points were used to evaluate the wind field. Results indicated that natural ventilation was prejudiced in the posterior region of the second scenario. However, at local level most of the points of comparison within the maximum occupancy model indicated better ventilation conditions comparing to the intermediate model.