An accelerated deflagration in an obstructed rectangular semi-confined chamber has been simulated with three different cofigurations for the obstacles position. The simulations are performed with the in-house CALIF 3 S-P 2 REMICS software developped at IRSN. Two approaches have been considered. The first is based on a statistic description of the turbulence and on a turbulent flame-speed closure approach for combustion. The second one uses a LES approach for turbulence description. The combustion is modelled using a virtually thickened flame formalism (TFLES) combined with a dynamical determination of the sub-grid scale flame wrinkling factors to handle unresolved contributions.