Large eddy simulations (LES) on the single-phase flow driven by a pitched blade impeller in a baffled stirred tank reactor were performed. The geometry, and operation conditions (defined in terms of Re=7,300) were chosen to comply with the experimental work by Schafer et al. As the turbulence in stirred tanks is strongly off-equilibrium, no straightforward criteria with respect to spatial and temporal resolution of the simulations call be formulated, and experimental validation becomes of prime importance. In this study, the influence of the resolution, and the specific choice of the subgrid-scale model (standard Smagorinsky model, and structure function model) on the simulated flow field were investigated.