The effect of interfacial waves on the turbulence structure of stratified air/water pipe flow

The turbulence structure of the gaseous phase in a stratified air/water pipe flow is investigated through a combination of three experimental approaches: PIV, conductance probes and hot-wire anemometry. Original velocity field measurements in the air phase were successfully achieved by using water droplets as tracer particles. The resulting measurements from this campaign describe a wide range of underlying mechanisms that govern the complex interplay between the flow dynamics of the gaseous phase and the interfacial flow pattern. One of such mechanisms is the generation of strong vortical structures in the wake of a wave-crest. The intensity, the size and the occurrence frequency of these structures depend strongly on the two-phase flow rate combination and their presence imposes changes to the turbulent energy cascade.