The hydrodynamics within a liquid/liquid slug flow in a micro-capillary reactor is characterized by complex vortex structures, both within the disperse and within the continuous phase. Usually, one of the phases exhibits good wetting of the wall, while the second phase exhibits poor wetting. This is why we expect a (continuous) thin film of the wetting phase along the wall. We compute this complex two-phase flow by means of a finite-volume method (FVM), whereas the interface is captured by a modified level-set method. Hence, from our numerical simulations we obtain the detailed topology of this two-phase flow, the position of the interface, as well as the thickness of the thin wall film of the continuous phase. With regard to the thickness of this wall film in liquid/liquid systems, very little information is available in literature. Of course, the hydrodynamics of this two-phase flow is the basis for any species transport computations within such micro-capillary reactors.
We discuss in detail the topology of this two-phase flow, as it develops for various parameters. Moreover, a careful comparison of experimental and theoretical findings on the wall film thickness is presented.