The present work aims to develop a modelling approach for the simulation of multiphase stirred tank with floating particles, suitable for up-scaling studies. Multiphase numerical modeling is used for predicting velocity profiles in stirred liquid. Free surface is evaluated from gas-liquid phase interaction. Transient time is incorporated in simulation. Entire simulation is run in this mode. It includes impeller start-up phase from zero to the full speed. The methodology is demonstrated on a case of published stirred tank design previously analyzed by experimental methods. Scale-up of stirred tanks is a frequently faced problem, which is difficult in cases of multiphase systems, especially with floating particles. The methodology presented in this work is directly applicable in practical problems concerning the scale-up of such complex multiphase systems. Free surface effect on velocity profile and on drawn-down location of solids is presented. This is usually omitted and simplified as a flat surface.
