Experimental Study of Downburst Wind Flow over a Typical Three-Dimensional Hill

To achieve a comprehensive understanding of three-dimensional (3D) wind field and the speed-up phenomenon in downburst flow over 3D hilly terrain, succession laboratory tests utilizing 12 hill models with cosine-squared cross-section was conducted using physical simulator jet diameter 0.6 m. By placing strong horizontal region vertical region, corresponding profiles for both velocities were measured. It found that flowed predominantly crest case low hills, whereas around body became increasingly pronounced as height increased. In addition, where velocity exceeds impinging velocity, identified, to move from two sides Accordingly, most significant topographic multipliers all locations on might appear at crest, foot, or elsewhere, depending largely height. Among cases, maximum multiplier 1.12, occurred ridge, while ratio 5/12. Additionally, empirical equations are presented facilitate determination loads induced by an isolated hill.