ABSTRACT The present state of the techniques for simulating turbulent flows is reviewed, from the oldest transport models of turbulence to the recent approaches, which try direct simulation of turbulent fields; particular relevance has been given to two-equation closure models. The analysis will be limited to single phase incompressible flow. The aim is to analyse strengths and limits of the different models, in order to evaluate the type of application they can be employed for and to give indications for the choice of the most efficient model. Considering the importance and wide diffusion in chemical engineering applications of the stirred tank reactor, this type of apparatus will be considered in greater detail; in fact, in spite of its relative mechanical simplicity, it has a very complex hydrodynamics: the models proposed for its description and their performances will be compared. The way in which a chemical reaction can be handled in the different models will also be reviewed shortly.
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