(2010), 'Experimental investigation of tornado-like vortex dynamics with Swirl Ratio: The mean and turbulent flow fields', J. (2008), 'Swirl ratio effects on tornado vortices in relation to the Fujita scale', Wind Struct., 11(4), 291-302. (2011), 'Behaviour of guyed transmission line structures under tornado wind loading', J.

(2008), 'Design, construction and performance of a large tornado simulator for wind engineering applications', Eng. (2010), 'Tornado induced wind loads on a low-rise building', J. (2005), The Rankine vortex model (Doctoral thesis). (1974), 'Structural analysis of tornado-like vortices', J. (2003), 'Pressure distribution on a cubical modeling tornado-like flow', Proceedings of the 10th Intl Wind Engineering Conf., Texas, Tech. (1998), 'Topographic influences on tornadoes in Pennsylvania', Preprints, Proceedings of the 19th Conference on Severe Local Storms, Amer.

(1984), 'Translation effects on simulated tornadoes', J. (1973), 'The dependence of core radius on swirl ratio in a tornado simulator', J. Washington, D.C., USA, American Geophysical union. (1993), Tornado: Its structure, dynamics, predictions and hazards. on Wind Effects on Buildings and Structures, Saikon, Tokyo. (1971), 'Tornado effects on building and structures with laboratory simulation', Proceedings of the 3rd Int. (2006), 'Effect of upstream hills on design wind load: a computational approach', Wind Struct., 9(1), 37-58. (2004), 'Numerical evaluation of turbulent flows over complex terrains: A review', J. (2014), 'Wind flow simulations on idealized and real complex terrain using various turbulence models', Adv. New FSUR values are produced for shallow and steep hills. Besides, the presence of the hill is also seen to relocate the center of tornadic flow.

It is observed that the effect of the hill on the radial and vertical component of the flow is more pronounced, compared to the tangential component. The effects of the hill on the radial, tangential and vertical flow components are assessed. A modified fractional speed-up ratio (FSUR) evaluation technique, appropriate to the complexity of the tornadic flow, is then developed. The tornado wind field obtained from the numerical simulations is first validated with previous experimental and numerical studies by comparing radial and tangential velocities, and ground static pressure. Steady state Reynolds Averaged Naiver Stokes (RANS) equations closed using Reynolds Stress Turbulence model are used to simulate stationary tornadoes. The effects of steep and shallow hills on a stationary tornado-like vortex with a swirl ratio of 0.4 are simulated and quantified as Fractional Speed Up Ratios (FSUR) at three different locations of the vortex with respect to the crests of the hills.

Tornado simulator 3