“…The influence of buoyancy forces on the airflow structure (thermal plume development, smoke spreading, etc.) depends primarily on the ventilation grade of the enclosure containing the fire-source [6], e.g., whether the enclosure is unventilated, mechanically ventilated (controllable) or naturally ventilated [6,7]. In the latter case, it is crucial to evaluate the effects of the external wind forces, as compared to the buoyancy forces, on the indoor airflow, in order to develop a mathematical model to describe the phenomenon.…”