On wall fire interaction in a small pool fire: a large-eddy simulation study

Large-eddy simulation (LES) with stochastic fields (SF) method is used to simulate a pool fire in a compartment for different distances from the compartment sidewalls. In our previous work (Jangi et al., 2016) [24], we have formulated and validated LES-SF method for modeling pool fires. Here we use the same approach to study the wall-fire interaction. For this purpose, two cases are presented. In one case the pool is located at the center of the compartment floor far from all sidewalls, referred to as case C. In another case the pool is in the vicinity of a sidewall, referred to as case W. In both cases, it is shown that pool fires are not a fully non-premixed flame but they can involve some levels of premixed combustion, especially in the form of ignition process in fuel-lean mixtures. This is more evident in case C when the pool is far from the walls. Results in case C show that flow is mainly driven by crosswise vortices, whereas for the case W, the flow is driven by longitudinal vortices. Depending on the distance for the sidewall, two mechanisms for the fire intermittency are identified: in case C the intermittency is mainly due to quenching and re-ignition, whereas in case W, it is essentially due to the interaction between flow and the sidewall.