This work aims at a comprehensive analysis of the capabilities of commercially available Computational Fluid Dynamics (CFD) tools for engineering systems involving complex geometries and two-phase ﬂows. Three different process engineering case studies were selected to examine the liquid-solid and liquid-liquid interactions in ﬂows characterised by sophisticated geometrical boundaries and inherent ﬂow complexity.
Packed bed reactors were used as a benchmark for the liquid-solid interactions. Local ﬂow ﬁeld, pressure drop, dispersion and mass transfer represent the investigated factors. The Kelvin-Helmholtz instability and a droplet rising in a quiescent medium were the two selected systems for the liquid-liquid interactions. For the ﬁrst system, the developed models were able to capture accurately the wave propagation and the developed ﬁnger-like structures. For the second one, the droplet shape and terminal velocity were thoroughly investigated. A new technique for the quantitative comparison of experimental and numerical results with respect to the droplet shape was presented. All developed rigorous CFD models were validated against experimental data or correlations found in the literature.