Turbulent flow and thermal characteristics of fire and ridge interaction and effects of wind velocity and ridge height

• 3D plume and thermal fields are analyzed for wildfire and wake interaction. • The presence of fire weakens the recirculation flow, increases wind velocity downstream. • Increasing wind velocity and ridge height generally increase turbulent kinetic energy and temperature fluctuations. Wildfires in the atmospheric boundary layer can generate significant heat and alter the local micro-scale flow dynamics. Understanding the effects of fire flames on turbulent flow dynamics is crucial for model development and effective fire management. While the flow and flame dynamics of wildfires have been extensively studied on flat and inclined surfaces, they have rarely been explored in rough terrain. To investigate the three-dimensional flow and flame interaction between wildfires and wake flow, large eddy simulation (LES) was employed to simulate the interaction between the wake and flame of a line fire located behind a ridge. The results show that flame temperature is higher near the ground surface, exhibiting strong intermittent behavior. The Q-criterion and Y vorticity are lower near the ground but increase significantly at higher elevations. The presence of fire reduces the recirculation flow, increases wind velocity downstream, updraft along the leeside of the ridge and downdraft above the ridge. Increasing wind velocity and ridge height tend to induce stronger chaotic cyclic flow behavior, leading to more pronounced fluctuating flame puffing.