GIS支持下的街区毒气扩散过程建模与模拟

Modeling and Simulation of Toxic Gas Dispersion in Urban Streets Supported by GIS

运用GIS与计算流体力学(computational fluid dynamics,CFD)的相关原理和方法,建立了一个街区尺度毒气扩散过程高分辨率建模、模拟的框架模型,探讨了街区下垫面快速建模、空间连续场表达、扩散过程模拟与可视化等关键技术,对建筑物扰动下近地面浓度扩散的过程及特性进行了模拟与分析。实验结果表明,GIS和CFD模型的耦合应用,能够较好地揭示建筑群中气云扩散和浓度时空分布的特征;近地面气云输运受建筑物布局影响显著,建筑物周围毒气浓度同该处源距、方位、高度以及来流风向偏离程度存在密切联系,泄漏停止后建筑群中气云滞留时间较长,对人群健康构成潜在威胁。

An integrated approach incorporating computational fluid dynamics （CFD） and GIS technologies is explored to model and simulate the movement characteristics of released gases and the concentration distribution around buildings at the street level. Some key technologies including street canyon modeling, continuous field representation, numerical simulation and visualization of gas dispersion are presented. As a case study, a hypothetical continuous re- lease from a point source is modeled and simulated. The results show that, the proposed ap- proach is able to predict the 3D and dynamic dispersion process in urban streets. The time- varying concentration distributions near the ground highlight the influences of building ar- rangement on the dispersion. The sampling concentrations around buildings are strongly af- fected by the positions of sampling points relative to source, including difference in height, distance from the source, and angle from wind direction. The results also confirm that, in the streets the hazardous gas may stay longer, which constitutes a threat to public health and safety.