Are Tornado Vortex Generators fit for purpose?

Baker, C.J.; Sterling, Mark

doi:10.1016/j.jweia.2019.05.011

Cited by 24 publications

(4 citation statements)

References 15 publications

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“…Finally, it should be recognized that the ability of modelscale tornado simulators to accurately model realistic tornado vortices has also been questioned (Baker and Sterling, 2019). Continued studies on the impacts of different methods of simulating tornadoes, (e.g., Gillmeier et al, 2016;Kopp and Wu, 2017;Gairola and Bitsuamlak, 2019), will be important to understanding the current study and others like it in the proper context.…”

Section: Conclusion and Discussionmentioning

confidence: 95%

“…The reference velocity depends on the assumed length and velocity scales. Length scales are problematic in vortex-driven fluid-structure interaction studies (Refan et al, 2014;Baker and Sterling, 2019;Gairola and Bitsuamlak, 2019), but some reasonable estimate must be made in order to obtain the model scale gust averaging time for the reference velocity. Here we use a length scale of 1/100 and a velocity scale of 1/5.6 and 1/4.74 for the low swirl and high swirl ratio vortices respectively (assuming full-scale wind speed of 60 m/s) to evaluate the maximum 3 s gust (in full scale) wind speed of the translating vortex at or below the roof height (in nominally open terrain since no roughness elements were present and a smooth floor was used), which is used as the reference velocity.…”

Section: Reference Velocitymentioning

confidence: 99%

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Tornado-Induced and Straight-Line Wind Loads on a Low-Rise Building With Consideration of Internal Pressure

Roueche

Prevatt

Haan

2020

Front. Built Environ.

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Tornado and straight-line wind events are often discussed and compared in terms of their intensity, e.g., maximum wind speed, however, it is unclear to what extent tornadoinduced and straight-line wind-induced wind loads are equivalent even for the same nominal intensity. This lack of understanding inhibits both tornado design philosophies and policies, and communication of tornado risk to the public. This study directly compares existing wind tunnel databases of tornado-induced and straight-line windinduced pressures, for a similar building model, to evaluate to what extent the induced surface pressures on a typical building differ. The existing datasets used in the study are enhanced with a numerical internal pressure model to facilitate the comparison across a range of opening configurations that would be common in typical buildings. The analysis finds that differences are most pronounced in the overall distribution of pressures across the building surface, and in the magnitudes of pressures in regions of strong flow separation. However, overall the magnitudes of the peak tornado-induced pressures are reasonably similar to straight-line wind-induced pressures, with tornadoinduced pressures on average 13% higher than equivalent straight-line wind-induced pressures. Ultimately, this study demonstrates a framework for such comparisons, while recognizing key sources of uncertainty and further research needs.

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Section: Conclusion and Discussionmentioning

confidence: 95%

Section: Reference Velocitymentioning

confidence: 99%

Tornado-Induced and Straight-Line Wind Loads on a Low-Rise Building With Consideration of Internal Pressure

Roueche

Prevatt

Haan

2020

Front. Built Environ.

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“…Tornado-like vortex generators can also model one and two-cell vortices (Haan et al, 2008;68 Tang et al, 2018), and improved the understanding of the vortex breakdown during the 69 transition between one and two-cell structure (Church and Snow, 1985). However, Baker and Sterling (2019) recently questioned the efficacy of tornado simulators to reproduce full-scale 71 tornadoes. The authors looked at various dimensionless group to evaluate the performance of 72 several tornado simulators with regards to dynamic, kinematic and geometric similarities.…”

Section: Introductionmentioning

confidence: 99%

Windborne debris trajectories in tornado-like flow field initiated from a low-rise building

Bourriez

Sterling

Baker

2020

Journal of Wind Engineering and Industrial Aerodynamics

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This paper examines compact debris flight in tornado-like flow fields. The 6 research focuses on physically simulating a specific tornado-like vortex and on investigating 7 windborne debris flight with and without a low-rise building model. The low-rise building 8 model, 1/8 th scale with regard to the vortex core radius, was used to initiate the flight of Styrofoam spheres from its top. Debris motion was recorded using three high-speed cameras and data reduction was performed on open-source OpenPTV software. Flow field characterisation showed that including a building model does not considerably affect the averaged flow field but only the local instantaneous flow field. Debris flight analysis shows that the mean flight distance is not affected by the building model, but a change in the initial direction occurs. Comparison between local wind flow field and initial debris velocities shows good agreement, and therefore the variability in initial directions of the debris flight can be attributed to a wind-driven process. To compare with experimental data, experimental data were incorporated into debris flight equations to compute debris motion. Debris trajectories computed from experimental data show strong visual similarities with experimental trajectories and debris flight analysis presents good agreement with experimental data.

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“…and tornadoes (e.g. Davies-Jones, 1973;Pauley, 1988;Haan et al, 2008;Refan and Hangan, 2018;Baker and Sterling, 2019). Some of these methods require separate facilities or instrumentation that are designed to closely replicate the vertical structure of the windstorm, either by dropping or pushing masses of air on a surface similar to an impinging jet or drawing in air upwards and rotating it using turning vanes.…”

Section: Pbwe For Nonstationary Windsmentioning

confidence: 99%

Performance-based wind engineering framework for vertical structures subjected to nonstationary wind loads

Le¹

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Regarded as a rational analytical approach that enables more risk-informed decision making, performance-based engineering (PBE) has been widely endorsed by the wind engineering community for the design and analysis of vibrationsensitive structures such as tall buildings. Accomplished through modular stages that delineate a structure's capacity to satisfy performance objectives, the uncertainties, error propagation, and random properties of the structural system, the environmental hazard, and the estimation of losses incurred from damages can be systematically examined with great detail. This multi-faceted, holistic approach vi Robert W. Bordewieck Endowed Engineering Fund provided by the College of Engineering of Northeastern University are gratefully acknowledged. Any opinions, findings and conclusions or recommendations are those of the Author and do not necessarily reflect the views of the NSF, MathWorks Inc.

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Are Tornado Vortex Generators fit for purpose?

Cited by 24 publications

References 15 publications

Tornado-Induced and Straight-Line Wind Loads on a Low-Rise Building With Consideration of Internal Pressure

Tornado-Induced and Straight-Line Wind Loads on a Low-Rise Building With Consideration of Internal Pressure

Windborne debris trajectories in tornado-like flow field initiated from a low-rise building

Performance-based wind engineering framework for vertical structures subjected to nonstationary wind loads

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