“…While analytical solutions are available for simplified cases only, researchers in this field started concentrating on the numerical techniques rather than finding the exact solutions. A number of numerical techniques are available for the solution of population balance equations (PBEs), such as methods of moments, , weighted residual method, method of characteristics, , Monte Carlo simulation, finite difference methods, , and high resolution finite volume schemes. , These numerical techniques were also extended to solve multivariable population balance models for different chemical engineering processes, such as crystallization, fluidized beds, and aerosol formation, and for predicting the interacting hydrodynamics and mass transfer in liquid–liquid extraction columns. − Moreover, the finite difference, finite element, and spectral methods were applied to solving multivariable cell population balance models. − …”