CFD Analysis of Hydrodynamics in a Stirred Mixing Tank

Design and optimization of mixing tanks require the simultaneous consideration of multiple interdependent parameters, making experimental evaluation both costly and time-consuming. Computational Fluid Dynamics (CFD) provides a powerful alternative for predicting flow behaviour and guiding design decisions. In this study, ANSYS Fluent was employed to investigate the hydrodynamics of a laboratory-scale stirred tank equipped with different impeller geometries. Two modelling approaches were implemented: the Moving Reference Frame (MRF) and the Sliding Mesh (SM) methods. Turbulence was described using the k-ω SST model, and in selected cases, a multiphase analysis was performed using the Volume of Fluid (VOF) approach. Four impellers - two straight-blade impellers with different height-to-diameter ratios, one 45° pitched-blade impeller, and a six-blade Rushton turbine - were evaluated under various operating conditions. The influence of impeller geometry, clearance, and the presence of baffles on the flow field was examined. Experimental visualization was performed to validate the numerical results. The simulations showed good agreement with experimental observations, confirming the reliability of CFD as a predictive and cost-effective tool for mixer design and performance assessment.