吉柏锋, 柳广义, 尹旭, 瞿伟廉. 地面粗糙度对下击暴流风剖面特征影响[J]. 空气动力学学报, 2019, 37(3): 393-399. DOI: 10.7638/kqdlxxb-2018.0117
引用本文: 吉柏锋, 柳广义, 尹旭, 瞿伟廉. 地面粗糙度对下击暴流风剖面特征影响[J]. 空气动力学学报, 2019, 37(3): 393-399. DOI: 10.7638/kqdlxxb-2018.0117
JI Baifeng, LIU Guangyi, YIN Xu, QU Weilian. Effects of terrain roughness on downburst wind profile characteristics[J]. ACTA AERODYNAMICA SINICA, 2019, 37(3): 393-399. DOI: 10.7638/kqdlxxb-2018.0117
Citation: JI Baifeng, LIU Guangyi, YIN Xu, QU Weilian. Effects of terrain roughness on downburst wind profile characteristics[J]. ACTA AERODYNAMICA SINICA, 2019, 37(3): 393-399. DOI: 10.7638/kqdlxxb-2018.0117

地面粗糙度对下击暴流风剖面特征影响

Effects of terrain roughness on downburst wind profile characteristics

  • 摘要: 地面粗糙度是大气边界层中反映下垫面形态的重要指标,也是影响近地风场特征的重要因素。为研究地面粗糙度对下击暴流风剖面特性的影响,基于计算流体力学方法建立了下击暴流三维足尺模型,通过实验对数值模型进行了验证。通过调整粗糙元高度及分布密度来模拟自然界地面不同的粗糙类别,数值模拟了具有不同地面粗糙长度的下击暴流近地风场。结果表明:在距离风暴中心较近的位置(r ≤ 1.0Djet),地面粗糙度对下击暴流风场的影响并不明显,各径向位置的最大风速值和最大风速所在高度都基本不受地面粗糙度影响;在下击暴流冲击地面后沿径向发展的过程中,经过粗糙的地面,产生能量耗散效应,地面粗糙度对于下击暴流风剖面特征的影响逐渐显著,不同地貌下的竖直风剖面产生较大差异;在近地面高度,地面粗糙度对下击暴流径向风剖面影响显著且影响范围大,沿径向发展的方向下击暴流的风速随着地面粗糙长度的增加而下降更迅速;随着距离地面高度增加,地面粗糙度对径向风剖面的影响主要体现在远离风暴中心的区域。尽管下击暴流形成后沿径向扩散过程存在强度自然衰减过程,但在距离风暴中心较远的径向位置,当遭遇强下击暴流时,下击暴流引起的近地面强风仍然具有很大的威胁和破坏性,因此地面粗糙度对下击暴流风剖面特性的影响不能忽略,需要在风剖面模型中考虑地面粗糙度的修正。

     

    Abstract: Terrain roughness is an important index of reflecting ground undulation and shape in the atmosphere boundary layer, and is also the key factor affecting the near-ground wind field characteristics. In order to study the effects of terrain roughness on downburst wind profiles characteristics, a three-dimensional full-scale downburst model was established and validated by physical experiments. The variable terrain roughness was achieved by compiling program to adjust the uniform roughness element height and distribution density. The downburst wind fields with variable terrain roughness were numerical simulated. The results indicate that, at a close position from the center of the storm (r ≤ 1.0Djet), the effects of surface roughness for downburst wind field are not significant. The value and position of the maximal wind velocity are hardly affected by the terrain roughness. With the downburst impacting the ground and diffusing along the radial direction, the energy dissipation is significantly affected by the surface roughness, resulting in different vertical wind profile characteristics at different terrain roughness. The radial wind profiles are affected evidently by the terrain roughness near the ground, and it has a large range of affected area. The wind velocity of the downburst in the radial direction decreases rapidly as the rough length of the ground increases. With the height from ground increasing, the affected area of terrain roughness in the radial wind profile are mainly reflected far from the center of the storm. Although there is a natural intensity attenuation process in the radial diffusion, the near ground strong wind induced by the downburst is still threatening and destructive. The effect of ground roughness on the downburst wind profile cannot be ignored. It is necessary to consider the correction of terrain roughness in the downburst wind profile model.

     

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