Computational modelling of mixing tanks for bioprocesses: Developing a comprehensive workflow

This paper reports a computational modelling study of a mixing tank for bioprocess applications. A dual impeller mixer containing several probes is used with a mixing speed of 400 rpm. The single-phase transient model is validated against experimental measurements using torque and velocity profiles as the validation variables. A complete workflow is illustrated that addresses all the relevant steps in the modelling of mixing. Many assumptions that are commonly made are explored and their importance is demonstrated. The necessity of including the probes in the computational domain is illustrated. The grid and time-step size are examined, and the relationship between the two is explained. Two turbulence models for RANS equation closure are compared, and the efficacy of the appropriate solution methodology for each is described. The importance of using the correct near-wall treatment is shown. Overall, this paper presents a standardized framework for the modelling of mixing tanks with turbulent flow.