Downburst often occurs in the mountainous and hilly areas.At present,the research of downburst mainly concentrates on the steady wind field in flat terrain.To investigate the effects of slope terrain on downburst wind field,an impinging jet physical experiment and the large eddy simulation (LES) were used to test and simulate the wind field in flat and three different gradient slopes.The results indicate that the large eddy simulation capture the transient characteristics of wind field,and the maximum wind speed of the wind field during the whole life cycle of downburst appears when the vortex structure first arriving the crest of the slope.Except the crest of the slope has significant speed-up effect,other positions were not found this effect.Compared with the wind field on flat terrain,both horizontal and vertical wind speed have increased,and the wind speed-up factor,Mt,near the ground reached about 1.3.The position where turbulence intensity increases obviously including the foot of the slope and the area behind the crest,and other positions do not have the obvious increasing effect.With the increasing of the gradients,the amplification factor of turbulence intensity at the crest increases slightly.
Key words
downburst /
slope terrain /
impinging jet /
wind tunnel test /
Large eddy simulation /
speed-up effect
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