层状云播云线源非均匀、非定常输送扩散数值模拟

Numerical Simulation of Heterogeneous and Unsteady Transport and Diffusion of Line Seeding Sources within Stratus

大多数层状云播云线源输送扩散模式常采用一些不合理的假设 ,使得输送扩散过程中起重要作用的一些物理过程被忽略。烟团轨迹模式能够处理源参数和气象要素的时空变化 ,适用于各种尺度和各类源的输送扩散模拟。因此 ,本文建立了一个模拟层状云播云线源输送扩散的三维时变烟团轨迹模式 ,并考虑了地形、垂直风切变作用 ,播云参数的时空变化和线源的湿清除效应。增雨作业实例的数值模拟研究结果表明 :模拟的播云线源输送扩散特征与输送扩散的基本理论和一般规律相吻合 ,并且再现了非垂直 (与风向上 )多条播云线源非均匀非定常的输送扩散特点。浓度等值线水平、垂直分布均不规则 ,比均匀定常点源更为复杂 ,整体不满足高斯浓度分布 ,表明在这种情况下均匀定常模式已不适用。另外 。

Most transport and diffusion models usually use some questionable assumption, which can cause some important physical processes of transport and diffusion that is ignored. Puff trajectory model can deal with the temporal spatial variation of source parameters and meteorological elements, and can be used to simulate the diffusion of all kinds of scales and sources. Therefore, a 3 D puff trajectory model has been formulated to simulate the transports and diffusions of line seeding sources within stratus. Effects of topography and vertical wind shear, temporal spatial variations of seeding parameters and wet deposition are considered. The model results from a case study show that the general features of diffusion and transport are consistent with basic theory of diffusion, and represent the heterogeneity and unsteadiness of diffusion. Compared to diffusion of point source under homogeneous and steady condition, the horizontal and vertical concentration distributions are irregular, and more complex, Gaussian plume model can not longer be suitable for presenting them. In addition, the model can simulate the structures of line sources in detail.