Simulations of moving downbursts using CFD

Moving downbursts occur more frequently than stationary downbursts due to the presence of ambient boundary layer winds. However, past research works mainly concentrated on stationary downbursts but rare for moving ones. Since the Andrews A.F.B. Downburst event was well recorded and analyzed by many researchers, this paper presents a simulation study of the moving downburst event using Computational Fluid Dynamics (CFD). The computational results reveal that the length scale R which influences the horizontal profiles of radial velocity should take different values for the Front Flank Downburst (FFD) and Rear Flank Downburst (RFD). In different stages of a moving downburst, value of R is also different. Based on the modification of R, good agreements between the numerical results and the field data are achieved for wind speed and direction timehistory, ground pressure distribution. The outputs of this study will also be useful for dynamic analysis of windsensitive structures such as power transmission towers in thunderstorm prone areas.