In this contribution a Large Eddy Simulation together with the Artificially Thickened Flame approach is used to study a well known experimental set-up consisting of a rectangular dump combustor - ORACLES. The major drawback of artificially thickening the flame is that the interaction between turbulence and flame is altered. To compensate for the inability of small vortices to wrinkle the flame a subgrid scale wrinkling model has to be introduced. In this contribution the influence of the subgrid scale wrinkling on the flame front in a high Reynolds number flow is investigated. Moreover the influence of different approximations for the subgrid scale velocity on the prediction of the flow field and flame structure is studied.