CFD simulations of dense solid–liquid suspensions in baffled stirred tanks: Prediction of suspension curves

Mixing of solid particles into liquids within contactors mechanically agitated by stirrers is a topic of primary importance for several industrial applications. A great research effort has been devoted to the assessment of the minimum impeller speed (Njs) able to guarantee the suspension of all particles. Conversely, only little attention has been paid so far to the evaluation of the amount of solid particles that are suspended at impeller speeds lower than Njs. In some cases the loss in available interfacial area between particles and liquid could be reasonably counterbalanced by a decreased mechanical power, making it of interest to evaluate the percentage of suspended solids at different impeller speeds

► Solid–liquid suspensions in stirred tank are investigated by experiments and CFD. ► Both partial and complete suspension regimes are investigated. ► An original criterion to identify via CFD the unsuspended particles is proposed. ► For the first time, suspension curves are predicted via CFD.