Numerical study of turbulent flow fields and the similarity of tornado vortices using large-eddy simulations

• Four typical tornado vortices are successfully simulated using LES.
• Characteristics of force balances in the tornado-like vortices are summarized.
• Scaled flow fields agree well with those for the Spencer tornado.

Tornado vortices are investigated using large-eddy simulations of a single vortex evolving into a multi-vortex. Four typical tornado configurations, including a weak vortex, a vortex breakdown, a vortex touch-down and a multi-vortex, are investigated to provide detailed information on the turbulent flow fields. The force balances in the radial and vertical directions are also evaluated using axsymmetrically and time averaged results. The local corner swirl ratio is used as an index to describe the surface intensification and the geometry of tornado vortices; the similarity between the simulated tornadoes and a full-scale tornado in nature is examined. Good agreements between the data of scaled tornado in simulation and the observed data of the full-scale tornado in nature are achieved.