Earlier research works have elucidated that decrease in the clearance of the Rushton Turbine (RT) impeller of the baffled reactor vessel causes a transition from double loop pattern to single loop pattern with significant reduction in the power number. We observe similar flow behaviour when the diameter of the reactor vessel is increased from the standard conditions of the reactor vessel. The mean and turbulent flow fields associated with the baffled reactor vessels of various diameter agitated using the RT impeller were analysed using the Computational Fluid Dynamics technique so as to understand the hydrodynamic reasons causing changes in the flow behaviour with increase in the diameter of the reactor vessel. The increase in the diameter of the reactor vessel generates a low pressure zone below the impeller which deflects the discharge streams and trailing vortices towards the bottom surface of the reactor vessel, causing the formation of single loop pattern. The downward propagation of trailing vortices weakens the flow separation regions behind the impeller blades; which in turn decreases the form drag and power number of the impeller. The higher magnitudes of axial velocity, vortex and turbulence activity from the impeller up to bottom surface of the reactor vessel as well as inferior entrainment of air makes the larger diameter vessel as a suitable option for the solid-liquid suspension process.