Centrifugal pumps are an integral part of process and chemical industries around the globe. The flow within vaneless volutes of centrifugal pumps is highly turbulent and three-dimensional. Conventional flow modelling techniques are usually incapable of capturing these complex flow structures. Moreover, use of 2-equation turbulence models in Computational Fluid Dynamics (CFD) cannot resolve the turbulent flow structures in pump's volutes. Visualisation of these complex and turbulent flow structures is very important in order to design the volutes appropriately. In the present study, Large Eddy Simulation (LES) based turbulence modelling approach has been used to analyse the complex flow structures in the volute of a commercial centrifugal pump. LES is more accurate in resolving larger eddies, while smaller eddies are modelled. Hence, flow predictions using LES are more realistic. It has been noticed that the interaction between the impeller blades and the tongue gives rise to flow non-uniformities in the volute. These flow non-uniformities are caused by the generation and subsequent propagation of three-dimensional complex turbulent flow structures. These flow structures absorb energy from the flow, imparting considerable head losses.