Hydrodynamic mechanisms in the horizontal slug pattern

The slug flow pattern is associated with an intensive mixing zone at its frontal region, where the fast-moving liquid slug front overruns the substrate film ahead. This mixing zone demonstrates intense fluctuations and asymmetry of the various flow characteristics, which clearly can not be treated analytically. An attempt to provide some insight into the complexity of the hydrodynamic mechanisms in the mixing zone is made by applying the k-l, k-ε{lunate} models and numerically evaluating the various hydrodynamic characteristics. Particular boundary conditions at the free-moving interface have been developed and incorporated in the numerical simulation.