The effects of edge radius on wind tunnel tests of low-rise buildings

Models used for the wind tunnel testing of structures are commonly fabricated using additive manufacturing techniques, such as 3D printing; however, the corners of the models can sometimes be rounded with some radius of curvature R, rather than be perfectly sharp. Should the edge curvature of these models be too large, the aerodynamics of these models can be significantly altered leading to unrealistic wind load estimations. To address this issue, a series of wind tunnel tests were conducted on a generic low-rise building model with varying edge radii to: (1) determine the effect of edge curvature on surface pressures and (2) determine a limit on edge radii of wind tunnel models, above which, the aerodynamics of the model is no longer representative of that around the full-scale building. It was found that increasing edge radius produces a continual change in pressure fields within the vicinity of separation bubbles and conical vortices (depending on wind direction). Considering the current experimental setup, changes in mean pressure fields exceed measurement uncertainty when the edge radius R/H >similar to 1.3%, where H is building height. The subsequent changes in pressure fields also lead to discrepancies in area-averaged pressures, however, the effects appear to be limited to small areas near building edges whose surface areas are below about 2m2 for a low-rise building with a roof height of 4m and plan dimensions of 10m x 15m.

Automated summary

Wind tunnel testing was conducted on structures fabricated using additive manufacturing techniques to determine the impact of edge curvature on aerodynamics. It was found that increasing edge radius alters pressure fields near separation bubbles and conical vortices, exceeding measurement uncertainty when the ratio of edge radius to building height is above approximately 1.3%. This leads to discrepancies in area-averaged pressures, particularly affecting small areas near building edges with surface areas below 2m2 for a low-rise building.