RANS CFD modeling of the flow around a thin windbreak fence with various porosities: Validation using wind tunnel measurements

Abstract

In computational fluid dynamics (CFD) simulations of airflow in built environments, the porous-jump model is commonly used to represent extremely thin porous windbreak fences, which have much smaller sizes than the neighborhood computational cells. However, owing to the limited quantitative validation studies that include turbulence characteristics, no clear guidelines exist on modeling such thin porous fences in CFD simulations. In this study, pressure loss coefficients of porous materials with various porosity values and opening shapes were determined using a small wind tunnel while the velocity and turbulence statistics behind the fences were measured in an atmospheric boundary layer wind tunnel. Two separate CFD models based on the Reynolds-averaged Navier–Stokes equation and porous-jump models were used to mimic the airflow in each wind tunnel and then they were validated using the experimental results. The results showed that the pressure loss was accurately predicted by CFD simulations. For wire-mesh fences, a good agreement was obtained between experimental and numerical results for the mean streamwise velocity and turbulent kinetic energy (TKE), whereas the velocity deficit and TKE were overestimated and underestimated, respectively, for the non-wire-mesh fences. This study can be used to improve the performance of thin porous windbreak fences.