Numerical Investigation of the Effect of Downburst Wind on Buildings with Various Geometrical Shapes

Abstract

A “Downburst” is an important weather phenomenon in which an airmass comes down with high velocity towards the ground from the cloud level during a thunderstorm. Thunderstorms occur frequently in the eastern and north-eastern part of India. Thunderstorms over Gangetic West Bengal and Assam is popularly known as ‘Kalbaishakhi’ and ‘Bardoisila’ respectively. Severe thunderstorms are known to cause detrimental impact on various facets of national activity like civil and defense operations, aviation, space vehicle launching, agriculture in addition to its damage potential to life and properties of human beings and animals. Extreme wind conditions during thunderstorm downburst also cause extensive damages to building structures. This happens when the aerodynamic loads due to high speed downburst wind significantly exceed the design loads of the building structure. Flow patterns and pressure distribution around building structures of different geometrical shapes under the influence of downburst through numerical simulation is the main subject of study in the present paper. Commercially available software ANSYS CFX 16 solvers have been used for the numerical simulation. The study shows that the flow pattern around the buildings and the pressure distribution on the building surfaces are significantly influenced by building shape.

Keywords: Downburst, streamline pattern, pressure coefficient, building shape, macro flow dynamics