Visualization of flow structures around a gable-roofed building model in tornado-like winds

Tornadoes are violently rotating columns of air extending from thunder storms to the ground. While extensive studies have been conducted to assess wind loads and flow structures around building models in strong winds, most of the previous investigations were conducted with straight-line winds. Bienkiewicz and Dudhia (1993) found that the wind loads acting on building models in tornado-like winds would be significantly higher (3–5 times) compared to those in straight-line winds with the same wind speed. This suggests that it is incorrect, or at least incomplete, to use a conventional straight-line wind tunnel running at maximum tornado wind speed to investigate wake flow features as well as the resultant wind loads acting on buildings in tornado-like winds. While several studies on building models in tornado-like winds have been conducted recently by measuring wind loads and/or surface pressure distributions (Sengupta et al. 2008; Mishra et al. 2008a, b), very little in the literature can be found to provide detailed flow field measurements to elucidate the flow–structure interactions of building models with tornado-like winds. In this communication, we report an experimental study to quantify the characteristics of the wake vortex and turbulent flow structures around a gable-roofed building model in tornado-like winds using a high-resolution particle image velocimetry (PIV) system. The objective of the present study is to elucidate underlying physics for a more accurate prediction of damage potentials of tornado-like winds to buildings.