城市大气环境的大涡模拟研究进展

本文回顾城市大气污染扩散的研究实践与进展, 介绍城市大气环境流动的特点和用现代计算流体力学手段开展城市大气环境的大涡模拟研究方法, 包括: 数学模型, 控制方程、亚网格湍流模式、定解条件及其数值方法. 其中, 重点介绍中尺度到微尺度的耦合模型与适用于复杂城市下垫面(满足大涡模拟分辨率要求且计算量较小)的组合模型;并给出实际算例和结果分析, 包括准确度的统计估算和湍流特性等. 最后, 讨论城市大气环境数值模拟方法进一步改进的方向和城市大气环境流动与污染物扩散数值研究应重点关注的几个问题.

Research advances in large eddy simulation of urban atmospheric environment

In this paper, we review practices and progresses in the study of pollution dispersion in urban atmosphere. We introduce the inherent features of urban environmental flow, as well as the application of a modern computational fluid dynamic (CFD) method, namely, the large eddy simulation for the study of urban atmospheric environment. We describe the mathematical model, governing equations, subgrid scale model, well-posed initial-boundary conditions and numerical method. In this paper, we focus on a coupling scheme between meso- and micro-scale motions, and a combined underlying surface model for the complex urban canopy, which satisfies the resolution requirements with relatively lower computing load. Practical simulations are presented and analyzed, including the statistical estimation of reliability and the turbulent characteristics, etc. Finally, further improvements needed for numerical methods of urban environment simulations are pointed out, and a number of key scientific problems are raised for numerical studies on urban environmental flows and pollution dispersion.