The interaction between the natural ambient winds found in the atmospheric boundary layer (ABL) and buoyant flames is crucial in broad applications in the scientific and engineering fields. Unlike the buoyancy-driven pool fires in still air that have been studied extensively, the complexity of physics changes significantly in wind presence. This study aims at analysing the characteristics of boundary-layer turbulence in the presence of large fires. The eddy dissipation concept, finite volume discrete ordinate method, and one k-equation model are used for combustion, thermal radiation, and sub-grid scale closure using the Large-Eddy Simulation (LES), respectively. A numerical model on simple cases is validated first to assess its capability to reproduce available experimental observations for a purely buoyant fire in still air. A forced-flow boundary layer combustion in a small chamber with a smooth inflow is further considered. In general, good agreement between the simulation results and available experimental data was achieved for temperature and velocity profiles. The unsteady inflow condition used to consider incoming atmospheric turbulence is generated through a precursor simulation. The wind interaction with the line fire changes the atmospheric boundary layer profile affecting the heat transfer ahead of the flame, thereby creating counter-rotating structures downstream. It is shown that the buoyancy-dominated flow due to the flame reaction induced local pressure variation and perturbed shear flow near the ground, thereby altering the wind speed through which the plume rises. Richardson number was also used as a dominant non-dimensional group to analyse the variation of enhanced flow vertical velocity with distance from the fire source. Thus, it is understood that the pronounced longitudinal shear spreading at the surface affects the behaviour of short term or puff releases, suggesting the shedding of small eddies during the combustion process.

在大气边界层 (ABL) 中发现的自然环境风与浮力火焰之间的相互作用在科学和工程领域的广泛应用中至关重要。与已被广泛研究的静止空气中浮力驱动的池火不同，物理的复杂性在风的存在下发生了显着变化。本研究旨在分析存在大火时边界层湍流的特征。涡耗散概念、有限体积离散纵坐标法和一个 k 方程模型分别用于使用大涡模拟 (LES) 进行燃烧、热辐射和亚网格尺度闭合。首先验证简单情况下的数值模型，以评估其再现静止空气中纯浮火的可用实验观察结果的能力。进一步考虑了流入平稳的小室中的强制流动边界层燃烧。一般而言，模拟结果与可用实验数据之间的温度和速度分布图实现了良好的一致性。用于考虑进入的大气湍流的不稳定流入条件是通过前兆模拟生成的。风与火线的相互作用改变了大气边界层剖面，影响火焰前方的热传递，从而在下游形成反向旋转结构。结果表明，由于火焰反应引起的浮力主导流引起局部压力变化和地面附近的扰动剪切流，从而改变羽流上升的风速。理查森数也被用作主要的无量纲组来分析增强的流动垂直速度随距火源距离的变化。因此，可以理解的是，表面上明显的纵向剪切扩散会影响短期或喷气释放的行为，这表明在燃烧过程中小涡流的脱落。