The dispersion of air pollutants emitted from industries has been studied ever since the dawn of industrialisation. The present work focuses on investigating the effect of negative atmospheric temperature gradient and the plume stack orientation of two individual equal-height stacks on the vertical rise and dispersion of the plume. The study carried out upon three-stack layout configurations namely inline, 45° and non-inline, separated by an inter-stack distance of 12 times the exit chimney diameter (12 D) and 22 times the exit chimney diameter (22 D) in each case over the two temperature gradients of −0.2 K/100 m and −0.5 K/100 m. The turbulence is modelled using realisable k-ε model, a model used in the FLUENT flow solver. In the case of the inline configuration, the upwind plume shields its downwind counterpart, which in turn allows for higher plume rise at a given temperature gradient. The plume oscillates more in the case of inline than 45° and non-inline cases. Also, for a temperature gradient of −0.5 K/100 m, the plumes oscillate violently in the vertical direction, mainly because, with the initial rise of the plume, cold air from higher altitudes moves down and forms a layer of lower temperature closer to the ground. The present study is important to highlight the plume dispersion characteristics under negative temperature gradient conditions.

自工业化曙光以来，就一直研究工业排放的空气污染物的扩散。目前的工作集中在调查负的大气温度梯度和两个单独的等高烟囱的烟囱方向对烟囱的垂直上升和扩散的影响。该研究基于三排布局配置进行，即直排，45°和非直排，其间距为烟囱直径（12 D）的12倍和烟囱直径（22 D）的22倍）分别在-0.2 K / 100 m和-0.5 K / 100 m的两个温度梯度上进行。使用可实现的k-ε模型（在FLUENT流动求解器中使用的模型）对湍流建模。在串联配置的情况下，迎风羽流屏蔽了其迎风羽流，这反过来又允许在给定的温度梯度下更高的羽流上升。直列情况下的烟流比45°和非直列情况下的振动更大。同样，对于-0.5 K / 100 m的温度梯度，羽流在垂直方向上剧烈振荡，这主要是因为随着羽流的初始上升，来自较高海拔的冷空气向下移动并形成一个温度较低的层地面。本研究对于强调负温度梯度条件下的羽流弥散特性非常重要。