Comparison between the Impinging Jet Model and Experimental Stationary Downbursts

The phenomenon of downdraft from thunderstorm cloud which after the touch-down spreads radially is well-known in both the meteorological and the wind-engineering community and has been under active investigation by a lot of authors since more than 50 years. In this paper, a simple impinging jet simulation has been compared with experimental downbursts in order to understand to which extent this approach can be considered realistic for practical applications. Wind tunnel experiments have been carried out at the University of Western Ontario’s WindEEE Dome Research Institute. The radial velocity was measured at various locations and the obtained profiles have been used as a reference for the comparison with the impinging jet, simulated by a steady-state Computational Fluid Dynamics (CFD) approach. As downbursts are highly transient phenomena, the impinging jet solution has been compared with the measured velocity profiles, which typically show three parts, i.e. ramp-up, plateau and dissipation, aiming to identify which part (if any) of the downburst lifecycle can be adequatelly represented by the steady-state numerical simulation.