This work aims at a reliable prediction of the flow dynamics in stirred tanks. The focus is on the free‐surface turbulent flow in an eccentric stirred tank by using the combination of detached‐eddy simulation and volume of fluid model. The flow field, profiles of the free surface, mean velocities, and the macroinstability phenomenon were explored and compared with the available experimental data. A reasonable representation of the free‐surface hydrodynamics was achieved. The findings indicate that the model and simulation strategies presented here can be used with sufficient confidence to predict the free‐surface hydrodynamics in stirred tanks.

To enhance the gas‐liquid mixing performance in stirred tanks, the grid‐disc impeller was designed by replacing the solid disc of the standard Rushton impeller with a grid disc. Gas‐liquid hydrodynamics of the new impeller was studied by employing the Eulerian‐Eulerian two‐phase model coupled with the dispersed k‐ε turbulence model. Rotation of the impeller was simulated with the multiple reference frame method. Flow field, gas holdup, and power consumption were investigated and compared with the standard Rushton impeller. The numerical method was validated by comparing the gas holdup with literature. The grid‐disc impeller performed better than the Rushton impeller in terms of gas dispersion performance, axial pumping capacity, and energy requirement, indicating its potential for gas‐liquid mixing applications.

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Despite extensive contributions have been made over the past several decades, there are still ongoing challenges in improving gas dispersion performance in stirred tanks. To that end, a stirred tank equipped with four semi-circular (SC) tube baffles was designed. Hydrodynamics in the stirred tank before and after aeration were studied. The turbulent fluid flow was simulated using the standard k-ε turbulence model. The gas–liquid two-phase flow was simulated by the Eulerian–Eulerian multiphase model and the k-ε dispersed turbulence model. The impeller rotation was modeled with the multiple reference frame (MRF) approach. Firstly, the grid independence test was made. By comparing the distributions of gas holdup in the flat-plate (FP) baffled stirred tank with literature results, the reliability of the numerical model and simulation method was verified. Subsequently, the flow field, gas holdup and power consumption of the SC and FP configurations were studied, respectively. Results show that the former can increase the fluid velocities and promote the gas holdup dispersion. Besides, it is energy-saving and has a higher relative power demand (RPD). The findings obtained here lay a preliminary foundation for the potential application of the SC configuration in the process industry.