This paper presents a parallel multidomain strategy to compute the turbulent flow in a closed vessel stirred by six fans. The method is based on running multiple instances of the same solver, working on different subdomains and communicating through small overlapping zones where interpolations allow to handle moving meshes. First the accuracy of this Multi Instances Solver Coupled on Overlapping Grids (MISCOG) approach is evaluated for the convection of a single vortex. Load balancing issues on parallel machines are discussed and a performance model is proposed to allocate cores to each code instance. Then, the method is applied to the LES of a closed vessel stirred by six fans. Mean and fluctuating fields obtained by the LES are compared to experimental data. Finally, the structure of the turbulence generated at the center of the vessel is studied and the mechanisms allowing turbulence to travel from the fans to the center of the vessel are analyzed.