A NUMERICAL-MODEL TO EVALUATE THE PERFORMANCE OF PRESSURE EQUALIZED RAINSCREEN WALLS

Advancements in Computational Fluid Dynamics (CFD) and numerical model ing techniques provide new approaches to quantify airflow around build ings and wind induced pressures on the building envelope. This paper d escribes the progress made on developing a numerical model to predict the performance of Pressure Equalized Rainscreen (PER) wall assemblies . The model is three dimensional and time dependent. The Navier Stokes Equations (NSE) are discretized using a control volume method. Extern al wall boundaries are treated with cyclic pressure differentials, the only fluid property available as a boundary condition from the experi ment. This paper presents the steps involved in the numerical model de velopment and the effect of static and dynamic parameters on the model predictions. Two types of wall assemblies, one representing an airtig ht air barrier system and another with a leaky air barrier system, are modeled. Predicted performances of both wall types are analyzed with respect to time and space. Preliminary model validation is performed b y comparing computed results with limited experimental data. The paper also includes some of these comparisons for various geometrical confi gurations of the PER wall assembly.