Graphic and parametric tools for preliminary design stage of natural ventilation systems

In this paper we developed a simplified graphical visualization to provide a preliminary understanding of aerodynamic pressure distributions around tall buildings and to estimate the best positions for ventilation openings. This graphical model is based on a database of pressure coefficients hold by parametrical twodimensional CFD (Computational Fluid Dynamics) simulations over several rectangular shape profiles. The pressure values are obtained by CFD simulations of a stationary flow (High Reynolds), with a K-epsilon turbulence model coupled with Navier-Stokes equations, by using Finite Elements Methods. Whilst turbulence model is well-known, the innovative application is the parameterization of the CFD simulations. The parameters considered here are the ratio between length and width of a rectangular shape and the wind direction (degrees azimuth). Our model adapts automatically to different shapes and various wind directions. Though not able to capture the same level of detail as the three-dimensional CFD simulations or experimental tests, it provides a rapid and intuitive guidance for architects at the preliminary design stage of a natural ventilation system. The final graphical visualizations, together with some simple recommendations, can be exploited by designers having no knowledge in aerodynamics