Numerical analysis of factors influencing the downburst wind profiles

Downburst is an outburst strong wind on or near the ground, and its wind profiles characteristics is significantly different from that of the traditional boundary layer winds. Numerical simulations were employed to investigate the factors influencing the downburst wind profiles. The downburst was simulated using the impinging jet model as the wind field model. Then, by varying the initial parameters of the downbursts, such as the initial jet diameter, the initial jet height and the jet velocity, the downburst horizontal wind profiles were calculated, including the vertical velocity profiles and the radial velocity profiles. Moreover, the influences of the initial parameters on the wind profiles characteristics were analyzed in detail. Calculated results indicate that, the maximum horizontal wind velocity V max increases with increasing the initial jet velocity V jet while their ratioV max /V jet decreases with increasing V jet The V max decreases with increasing the initial jet height and is little affected by the initial jet diameter. The height of the maximum horizontal velocity appeared increases with increasing the initial jet diameter while is little affected by the initial jet height and the initial jet velocity, and its value usually equals to 0.025 ∼ 0.045D jet. The radial position of the maximum horizontal velocity appeared shows linear increase approximately with increasing the initial jet diameter while decreases with increasing the initial jet height and the initial jet velocity, and its value usually equals to 1.0 ∼ 1.2 D jet.