Numerical simulation of downburst winds

Mason, Matthew S., Wood, Graeme S., & Fletcher, David F. (2009) Numerical simulation of downburst winds. Journal of Wind Engineering and Industrial Aerodynamics, 97(11–12), pp. 523-539.

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Abstract

The wind field of an intense idealised downburst wind storm has been studied using an axisymmetric, dry, non-hydrostatic numerical sub-cloud model. The downburst driving processes of evaporation and melting have been paramaterized by an imposed cooling source that triggers and sustains a downdraft. The simulated downburst exhibits many characteristics of observed full-scale downburst events, in particular the presence of a primary and counter rotating secondary ring vortex at the leading edge of the diverging front. The counter-rotating vortex is shown to significantly influence the development and structure of the outflow. Numerical forcing and environmental characteristics have been systematically varied to determine the influence on the outflow wind field. Normalised wind structure at the time of peak outflow intensity was generally shown to remain constant for all simulations. Enveloped velocity profiles considering the velocity structure throughout the entire storm event show much more scatter. Assessing the available kinetic energy within each simulated storm event, it is shown that the simulated downburst wind events had significantly less energy available for loading isolated structures when compared with atmospheric boundary layer winds. The discrepancy is shown to be particularly prevalent when wind speeds were integrated over heights representative of tall buildings. A similar analysis for available full scale measurements led to similar findings.

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ID Code: 70456
Item Type: Journal Article
Refereed: Yes
Keywords: Downburst, Microburst, Thunderstorm, Thunderstorm outflow
DOI: 10.1016/j.jweia.2009.07.010
ISSN: 0167-6105
Subjects: Australian and New Zealand Standard Research Classification > ENGINEERING (090000) > CIVIL ENGINEERING (090500) > Structural Engineering (090506)
Australian and New Zealand Standard Research Classification > ENGINEERING (090000) > INTERDISCIPLINARY ENGINEERING (091500) > Computational Fluid Dynamics (091501)
Australian and New Zealand Standard Research Classification > ENGINEERING (090000) > INTERDISCIPLINARY ENGINEERING (091500) > Fluidisation and Fluid Mechanics (091504)
Divisions: Current > Schools > School of Civil Engineering & Built Environment
Current > Institutes > Institute for Future Environments
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Copyright Owner: Copyright 2009 Elsevier Ltd.
Deposited On: 01 Jul 2014 00:13
Last Modified: 01 Jul 2014 23:01

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