Dynamical models of two‐dimensional downdraughts
Dynamical models of two‐dimensional downdraughts
复制标题
二维下沉气流的动力学模型
DOI：
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发表时间：
1980
期刊：
影响因子：
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通讯作者：
M. Moncrieff
中科院分区：
文献类型：
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作者：
A. Thorpe;M. Miller;M. Moncrieff
观测和数值模型数据表明下沉气流在强风暴的运动、结构和再生中起着至关重要的作用。本文使用数值模型和分析模型考虑了二维下沉气流动力学。在数值模型中，下沉气流由恒定的散热器产生和维持。模拟环境流入的调整以及由此产生的下沉气流和风暴单元的潜在再生。
为了阐明物理原理，还描述了稳定的分析模型，其中使用了下吸热力学的简单参数化。已经确定了两种不同类型的个体气流动力学，标记为对称和跳跃，允许对六种动态一致的上升气流和下降气流进行定性描述。特别地，分析了冷对称下降气流和冷跳跃型上升气流，前者具有负流出切变，后者具有正流出切变。这些解析解与数值模型开发的稳态非常吻合。
数值模型还用于描述下游和上游阵风锋的传播，这些结果与大气和水箱数据吻合良好。
Observational and numerical model data have indicated the crucial role of the downdraught in the motion, structure and regeneration of severe storms. This paper considers downdraught dynamics in two dimensions, using both a numerical and an analytical model. In the numerical model the downdraught is produced and maintained by a constant heat sink. The adjustment of an ambient inflow, and the resultant downdraught and potential regeneration of storm cells, is simulated.
To elucidate physical principles, steady analytical models are also described in which a simple parametrization of downdraught thermodynamics is used. Two distinct types of individual draught dynamics, labelled symmetric and jump, have been identified allowing a qualitative description of six dynamically consistent updraughts and downdraughts. In particular, a cold symmetric downdraught and a cold jumptype updraught are analysed, the former having negative, the latter positive outflow shear. These analytical solutions agree well with steady states developed by the numerical model.
The numerical model is also used to describe the propagation of downstream and upstream gust fronts, and these results are in good agreement with atmospheric and tank data.