Mixing Analysis in a Stirred Tank Using Computational Fluid Dynamics

Abstract

The numerical method of modelling and simulation was used to model the mixing performance in a stirred tank reactor. In spite of the great advances with which the field of the design of chemical reactors has moved, mixing is poorly understood and the design is generally unsophisticated. For this matter, the objective of the investigation is to characterize the flow field generated within the tank, analyse the degree of mixing and to relate the 𝒌-ε turbulent models. Several mathematical models like equations of continuity and momentum equations have been used in the simulation. The hydrodynamic behaviour was understood by velocity magnitude, the radial and axial velocities the volume fractions and the eddy viscosity plots. Eulerian-Eulerian multi-fluid model was simulated using the Eulerian-Eulerian multi-fluid model where the RANS standard 𝒌-ε model, RNG 𝒌-ε model and the Realizable 𝒌-ε model with a multiple reference frame approach were used to model the various parameters. Contours of eddy viscosity show the degree of mixing in the stirred tank. From the results, it can be observed that the standard 𝒌-ε and the realizable 𝒌-ε gave a uniform plot of eddy viscosity with standard 𝒌-ε being the best model and the RNG 𝒌-ε model producing a poor eddy viscosity plot. The velocity vector and contour plots were also simulated to determine the flow field in the stirred tank. The standard 𝒌-ε shows a better flow field than both the realizable and the RNG 𝒌-ε models. The standard 𝒌-ε gave a better results when compared.