CFD Analysis of Turbulence Models to Achieve the Digester Mixing Process

Abstract

Mixing efficiency defines the features of physicochemical and biological reactions carried out in reactors or digesters. The reason for this influence is because it conditions the heat and mass transfer. That is why the mixing level and intensity become important aspects to study to know the effects they have on the processes. Furthermore, it should be noted that most of the mixing processes are carried out under turbulent conditions. Mixing enhancement evaluation is achieved in two ways, that is, experimentally and performing simulations. Simulations are based on numerical methods approximating solutions to results in line with reality. In this context, turbulence models applied in systems have great influence on the final numerical solution and, therefore, on the interpretation of improved mixing in reactors. It is also necessary to consider the influence of rheology in these simulations, since the working fluid does not always have a linear stress-strain relationship. In this way, an analysis of turbulence models and their applications in mixing characterization and the adequacy of these models to the reactor configuration and operating conditions is carried out. Mention is also made of the experiences around the study of turbulence in mixing tanks.