Drawdown of Floating Solids in Stirred Tanks: Scale-up Study using CFD Modeling

October 14, 2011


Waghmare, Y., R. Falk, L. Graham, and V. Koganti, “Drawdown of Floating Solids in Stirred Tanks: Scale-up Study using CFD Modeling” Int. J. Pharm., 418:2(2011)243-253.


This work shows development of a scale up correlation using computational fluid dynamic (CFD) simulations for floating solids drawdown operation in stirred tanks. Discrete phase modeling (DPM) simulations were used in conjunction with the lab scale experimental measurements to develop a semi-empirical correlation for the prediction of rate of drawdown of floating solid particles. The rate was correlated to average liquid velocity at the free liquid surface. Since, this correlation is based on a fundamental hydrodynamic parameter, velocity, rather than an operating parameters such as the impeller speed, it can be used for a variety of impeller types and tank geometries. The correlation was developed based on the data obtained from the 2 L tank using four different tank designs and was validated against the data obtained from the 10 L scale tank. The correlation was further extended to the pilot and the commercial scale tanks ranging from 40 L to 4000 L scale based solely on the CFD model.

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