In this work, a Large Eddy Simulation (LES) model was used to simulate the transient premixed flame-vortex interaction, which is the key phenomenon determining dynamics and consequences of gas explosions. In particular, the effect of the grid resolution on the impact of the combustion sub-model was investigated. To this end, LES computations were run, with and without the combustion submodel, on three non-uniform unstructured grids with cell characteristic length varying in the ranges 2-3 mm, 1-2 mm and 0.5-1 mm. Numerical predictions were compared with literature experimental data. It has been found that the amount of detail explicitly resolved on the finer grid (having a resolution of the same order of magnitude as the laminar flame thickness) is such that, even without the combustion sub-model, the LES results obtained with this grid correctly match the experimental data in both quantitative (flame speed and flow velocity) and qualitative (shape and structure of the flame front) terms. (C) 2011 Elsevier Ltd. All rights reserved.