Numerical and Physical Simulation of a Thunderstorm Downburst

This paper describes work undertaken as a joint project between the University of Strathclyde (UoS) and the University of Birmingham (UoB) in the UK, aimed at simulating thunderstorm downbursts both physically and numerically. The UoB downburst simulator uses a 1m diameter, impinging jet with computercontrolled fans and flaps to physically simulate a downburst, with the data gathered used for calibration and validation of the numerical models developed at the UoS. These models, which are in an early stage of development, use novel inlet conditions to simulate the inflow, allowing more accurate and variable inflows. Wavelet analysis is used to compare the full-scale and physical simulation data, with correlation analyses (phaseplots) used to identify structures within the physical simulation flow field. Initial results show a good match between the physical simulations and full-scale, field data, and between the two sets of simulations.