Abstract: Recently few wind tunnel and computer model researchers reported that when a tornado goes over a hill the path of the tornado deviates. In this work further detailed study of the extent of path deviation for various ratios of tangential velocity to translational velocity are investigated. Wind tunnel, field and computer model data are investigated to examine the effects of topography (a ridges) on tornado path deviation (i.e. turns in tornado path while interacting with the topography). Field data from both Tuscaloosa (2011) and Mayflower (2014) tornados is considered in this study to examine effects of topography on tornado path deviation. Computer model is utilized to run six different ratios of tangential velocity to translational velocity (Vϴ/Vt) (i.e.1-4, 6, 8) and study the effects of changing this ratio on tornado path deviation. The topography shape considered in this work is a ridge. Results show that (Vϴ/Vt) ratio has significant influence on a tornado path deviation. As the ratio increases, the deviation shape changes from a straight line to single curvature then to double curvature. For ratio (Vϴ/Vt) < 2, the deviation shape is almost a straight line. For 2≤ (Vϴ/Vt) <4, the deviation shape becomes a single curvature shape. When the ratio (Vϴ/Vt) ≥4, the deviation shape changes to double curvature. Numerical results for (Vϴ/Vt) ≥4 is comparable to wind tunnel data. Therefore the computer model is considered for further investigation. The University of Arkansas (UA) computer model results for tornado path deviation shape are comparable to both experimental and field data.
Keywords: Tornado-terrain interaction; tornado path deviation; ridge effects on tornado path deviation; fluid-structure interaction, computational fluid dynamic.
Title: Ridge Effects on Tornado Path Deviation
Author: Nawfal Ahmed, R. Panneer Selvam
International Journal of Civil and Structural Engineering Research
ISSN 2348-7607 (Online)
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