A diverging wind system known as “downburst” is defined as a strong downdraft which induces an outburst of damaging winds on or near the ground. Severe wind damage in many parts of the world are often due to thunderstorm outflows and they therefore have a focal role in structural safety and design wind speed evaluation. Despite this, there is not yet a shared model for thunderstorm outflows and their action on structures. In this paper, an analytical model that simulates the horizontal mean wind velocity originated from a travelling downburst is proposed. The horizontal wind velocity is expressed as the vector summation of the stationary radial speed generated by an impinging jet, the downdraft translating velocity and the background wind velocity, where the thunderstorm is immersed. All parameters employed in the model are related to meteorological variables that are susceptible of statistical assessment. A parametric study is also developed and coupled with the analytical model in order to investigate several observed downburst events. The different parameters of the downburst such as downdraft diameter, touchdown position, translating downdraft speed and direction, intensity and decay period are estimated through the parametric study in order to reconstruct the space-time evolution of this event.

An advanced analytical model for simulating thunderstorm outflows

Massimiliano Burlando;Giovanni Solari
2019

Abstract

A diverging wind system known as “downburst” is defined as a strong downdraft which induces an outburst of damaging winds on or near the ground. Severe wind damage in many parts of the world are often due to thunderstorm outflows and they therefore have a focal role in structural safety and design wind speed evaluation. Despite this, there is not yet a shared model for thunderstorm outflows and their action on structures. In this paper, an analytical model that simulates the horizontal mean wind velocity originated from a travelling downburst is proposed. The horizontal wind velocity is expressed as the vector summation of the stationary radial speed generated by an impinging jet, the downdraft translating velocity and the background wind velocity, where the thunderstorm is immersed. All parameters employed in the model are related to meteorological variables that are susceptible of statistical assessment. A parametric study is also developed and coupled with the analytical model in order to investigate several observed downburst events. The different parameters of the downburst such as downdraft diameter, touchdown position, translating downdraft speed and direction, intensity and decay period are estimated through the parametric study in order to reconstruct the space-time evolution of this event.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11567/942975
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