Numerical simulation of stirred liquid-liquid systems

The numerical simulation of drop size distributions in stirred liquid-liquid systems requires, on one hand, the simulation of the flow field in the stirred tank and, on the other hand, the calculation of the population dynamical processes. These processes, in the considered application coalescence and breakage, describe how the number and the sizes of the drops in the dispersed phase change with time. In the presented approach, the (Reynolds-averaged) Navier-Stokes equations (with k -ε turbulence model), describing the turbulent flow in the stirred tank, are solved with a CFD code and the population balance equation, accounting for coalescence and breakage of the drops, is simulated with a population balance solver. The coupling of the two solvers is realized as a oneway coupling, i. e. the results of the CFD simulation are used for the calculation of the population dynamical processes. We will explain how the coupling can be realized, motivate why this type of coupling was chosen, and present simulation results. However, we will also discuss arising problems and risks of simulator coupling. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)